0000100517-24-000027 | 10-K | XBRL Viewer | United Airlines Holdings INC

Pension, Postretirement And Other Employee Benefit Plans (Tables)

12 Months Ended

Dec. 31, 2023

Reconciliation of the Change in Benefit Obligation and Plan Assets and Funded Status

The following tables set forth the reconciliation of the beginning and ending balances of the benefit obligation and plan assets, the funded status and the amounts recognized in these financial statements for the defined benefit and other postretirement plans (in millions):


	Pension Benefits
	Year Ended December 31, 2023		Year Ended December 31, 2022
Accumulated benefit obligation:	$	3,910	$	3,596

Change in projected benefit obligation:
Projected benefit obligation at beginning of year	$	4,181	$	6,473
Service cost	124		204
Interest cost	217		188
Actuarial (gain) loss	204		(2,186)
Benefits paid	(177)		(464)
Other	1		(34)
Projected benefit obligation at end of year	$	4,550	$	4,181

Change in plan assets:
Fair value of plan assets at beginning of year	$	3,467	$	4,626
Actual income (loss) on plan assets	281		(678)
Employer contributions	22		8
Benefits paid	(177)		(464)
Other	6		(25)
Fair value of plan assets at end of year	$	3,599	$	3,467
Funded status—Net amount recognized	$	(951)	$	(714)


	Pension Benefits
	December 31, 2023		December 31, 2022
Amounts recognized in the consolidated balance sheets consist of:
Noncurrent asset	$	21	$	44
Current liability	(4)		(11)
Noncurrent liability	(968)		(747)
Total liability	$	(951)	$	(714)

Amounts recognized in accumulated other comprehensive income (loss) consist of:
Net actuarial loss	$	(242)	$	(77)
Prior service cost	—		(1)
Total accumulated other comprehensive loss	$	(242)	$	(78)


	Other Postretirement Benefits
	Year Ended December 31, 2023		Year Ended December 31, 2022
Change in benefit obligation:
Benefit obligation at beginning of year	$	788	$	1,129
Service cost	4		9
Interest cost	42		30
Plan participants' contributions	67		69
Benefits paid	(177)		(179)
Actuarial (gain) loss	22		(270)
Benefit obligation at end of year	$	746	$	788

Change in plan assets:
Fair value of plan assets at beginning of year	$	48	$	49
Actual return on plan assets	1		1
Employer contributions	107		108
Plan participants' contributions	67		69
Benefits paid	(177)		(179)
Fair value of plan assets at end of year	46		48
Funded status—Net amount recognized	$	(700)	$	(740)

Amounts Recognized in Consolidated Balance Sheet and Accumulated Other Comprehensive Income (Loss)


	Other Postretirement Benefits
	December 31, 2023		December 31, 2022
Amounts recognized in the consolidated balance sheets consist of:
Current liability	$	(63)	$	(69)
Noncurrent liability	(637)		(671)
Total liability	$	(700)	$	(740)

Amounts recognized in accumulated other comprehensive income (loss) consist of:
Net actuarial gain	$	309	$	369
Prior service credit	222		335
Total accumulated other comprehensive income	$	531	$	704

Accumulated Benefit Obligation and Projected Benefit Obligation in Excess of Plan Assets

The following information relates to all pension plans with an accumulated benefit obligation and a projected benefit obligation in excess of plan assets at December 31 (in millions):


	2023		2022
Projected benefit obligation	$	4,407	$	4,045
Accumulated benefit obligation	3,767		3,461
Fair value of plan assets	3,435		3,287

Components Of Net Periodic Benefit Cost

Net periodic benefit cost (credit) for the years ended December 31 included the following components (in millions):


	2023				2022				2021
	Pension Benefits		Other Postretirement Benefits		Pension Benefits		Other Postretirement Benefits		Pension Benefits		Other Postretirement Benefits
Service cost	$	124	$	4	$	204	$	9	$	239	$	10
Interest cost	217		42		188		30		184		25
Expected return on plan assets	(251)		(1)		(306)		(1)		(283)		(1)

Amortization of unrecognized actuarial (gain) loss	8		(38)		120		(14)		170		(28)
Amortization of prior service credits	1		(112)		—		(112)		—		(123)
Special termination benefits - Voluntary Programs	—		—		—		—		—		31
Curtailment	—		—		—		—		(8)		—
Other	3		—		5		—		5		—
Net periodic benefit cost (credit)	$	102	$	(105)	$	211	$	(88)	$	307	$	(86)

The Company's expected Net periodic benefit cost (credit) for 2024 is as follows (in millions):


	Pension Benefits		Other Postretirement Benefits
Net periodic benefit cost (credit)	$	108	$	(78)

Assumptions Used for Benefit Plans

The assumptions used for the benefit plans were as follows:


	Pension Benefits
Assumptions used to determine benefit obligations	2023		2022
Discount rate	5.04	%	5.20	%
Rate of compensation increase	3.84	%	3.83	%

Assumptions used to determine net expense
Discount rate	5.20	%	2.90	%
Expected return on plan assets	7.53	%	7.16	%
Rate of compensation increase	3.83	%	3.83	%


	Other Postretirement Benefits
Assumptions used to determine benefit obligations	2023		2022
Discount rate	5.43	%	5.66	%

Assumptions used to determine net expense
Discount rate	5.66	%	2.82	%
Expected return on plan assets	3.00	%	3.00	%
Health care cost trend rate assumed for next year	7.00	%	5.60	%
Rate to which the cost trend rate is assumed to decline (ultimate trend rate in 2033)	4.50	%	4.50	%

Allocation of Plan Assets

Plan fiduciaries regularly review our actual asset allocation and the pension plans' investments are periodically rebalanced to our targeted allocation when considered appropriate. United's plan assets are allocated within the following guidelines:


	Percent of Total		Expected Long-Term Rate of Return
Equity securities	25-73	%	9	%
Fixed-income securities	14-53		8
Alternatives	3-27		8

Schedule of Change in Assumptions on Net Periodic Benefit Cost and Benefit Obligations


The table below shows the impacts of a change in certain assumptions on the 2024 net periodic benefit cost and the benefit obligations at December 31, 2023 (in millions):
	Pension Benefits		Other Postretirement Benefits
Impact on Benefit Obligation at December 31, 2023
100 basis points decrease in the weighted average discount rate	$	858	$	48

Impact on 2024 Net Periodic Benefit Cost
100 basis points decrease in the weighted average discount rate (a)	$	96	$	—
100 basis points decrease in the expected long-term rate of return on plan assets	35		—
(a) In general, as discount rates increase, the impact of changes in discount rates decreases. Therefore, these sensitivities cannot be extrapolated for larger increases or decreases in the discount rate. In addition, benefit cost is affected by other factors including, but not limited to, investment performance, contributions, demographic experience and other assumption changes.

Pension and Other Postretirement Plan Assets

The following tables present information about United's pension and other postretirement plan assets at December 31 (in millions):


	2023										2022
Pension Plan Assets:	Total		Level 1		Level 2		Level 3		Assets Measured at NAV(a)		Total		Level 1		Level 2		Level 3		Assets Measured at NAV(a)
Equity securities funds	$	1,265	$	74	$	3	$	134	$	1,054	$	1,183	$	58	$	26	$	114	$	985
Fixed-income securities	1,325		—		411		3		911		1,316		—		527		5		784
Alternatives	779		—		—		136		643		887		—		—		161		726
Other investments	230		13		87		3		127		81		6		16		5		54
Total	$	3,599	$	87	$	501	$	276	$	2,735	$	3,467	$	64	$	569	$	285	$	2,549
Other Postretirement Benefit Plan Assets:
Deposit administration fund	$	46	$	—	$	—	$	46	$	—	$	48	$	—	$	—	$	48	$	—

(a) In accordance with the relevant accounting standards, certain investments that are measured at fair value using the net asset value ("NAV") per share (or its equivalent) have not been classified in the fair value hierarchy. These investments are commingled funds that invest in equity securities and fixed-income instruments including bonds, debt securities, and other similar instruments issued by various U.S. and non-U.S. public- or private-sector entities. Redemption periods for these investments range from daily to semiannually.

Defined Benefit Plan Assets Measured at Fair Value Using Unobservable Inputs

The following table presents reconciliation of United's benefit plan assets measured at fair value using unobservable inputs (Level 3) for the years ended December 31, 2023 and 2022 (in millions):


	2023		2022
Balance at beginning of year	$	333	$	435
Actual income (loss) on plan assets:
Sold during the year	(50)		34
Held at year end	55		(39)
Purchases, sales, issuances and settlements (net)	(16)		(97)
Balance at end of year	$	322	$	333

Estimated Future Benefit Payments

The estimated future benefit payments, net of expected participant contributions, in United's pension plans and other postretirement benefit plans for the next ten years, as of December 31, 2023, are as follows (in millions):


	Pension		Other Postretirement
2024	$	268	$	112
2025	301		100
2026	323		88
2027	348		80
2028	373		74
Years 2029 – 2033	1,896		274

Participation in the IAM National Pension Plan

United's participation in the IAM National Pension Plan ("IAM Plan") for the annual period ended December 31, 2023 is outlined in the table below. The risks of participating in these multi-employer plans are different from single-employer plans, as United may be subject to additional risks that others do not meet their obligations, which in certain circumstances could revert to United. The IAM Plan reported $533 million in employers' contributions for the year ended December 31, 2022. For 2022, the Company's contributions to the IAM Plan represented more than 5% of total contributions to the IAM Plan. The 2023 information is not available as the applicable Form 5500 is not final for the plan year.


Pension Fund			IAM National Pension Fund ("IAM Fund")
EIN/ Pension Plan Number			51-6031295 — 002
Pension Protection Act Zone Status (2023 and 2022)			Critical (2023 and 2022). A plan is in "critical" status if the funded percentage is less than 65 percent. On April 17, 2019, the IAM National Pension Fund Board of Trustees voluntarily elected for the IAM Fund to be in critical status effective for the plan year beginning January 1, 2019 to strengthen the IAM Fund's financial health. The IAM Fund's funded percentage was 87.1% as of January 1, 2022.
FIP/RP Status Pending/Implemented			A 10-year Rehabilitation Plan effective, January 1, 2022, was adopted on April 17, 2019 that requires the Company to make an additional contribution of 2.5% of the hourly contribution rate, compounded annually for the length of the Rehabilitation Plan, effective June 1, 2019.
United's Contributions			$87 million, $75 million and $58 million in the years ended December 31, 2023, 2022 and 2021, respectively.
Surcharge Imposed			No
Expiration Date of Collective Bargaining Agreement			N/A

Leases and Capacity Purchase Agreements - Supplemental Cash Flow Information Related to Leases (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows for operating leases	$ 874	$ 919	$ 977
Operating cash flows for finance leases	21	13	18
Financing cash flows for finance leases	$ 311	$ 124	$ 216

Pension, Postretirement And Other Employee Benefit Plans - Estimated Future Benefit Payments (Details) $ in Millions	Dec. 31, 2023 USD ($)
Pension
Pension and Other Postretirement
2024	$ 268
2025	301
2026	323
2027	348
2028	373
Years 2029 – 2033	1,896
Other Postretirement
Pension and Other Postretirement
2024	112
2025	100
2026	88
2027	80
2028	74
Years 2029 – 2033	$ 274

Consolidated Balance Sheets (UAH) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Current assets:
Cash and cash equivalents	$ 6,058	$ 7,166
Short-term investments	8,330	9,248
Restricted cash	31	45
Receivables, less allowance for credit losses (2023—$18; 2022—$11)	1,898	1,801
Aircraft fuel, spare parts and supplies, less obsolescence allowance (2023—$689; 2022—$610)	1,561	1,109
Prepaid expenses and other	609	689
Total current assets	18,487	20,058
Operating property and equipment:
Flight equipment	48,448	42,775
Other property and equipment	10,527	9,334
Purchase deposits for flight equipment	3,550	2,820
Total operating property and equipment	62,525	54,929
Less—Accumulated depreciation and amortization	(22,710)	(20,481)
Total operating property and equipment, net	39,815	34,448
Operating lease right-of-use assets	3,914	3,889
Other assets:
Goodwill	4,527	4,527
Intangibles, less accumulated amortization (2023—$1,495; 2022—$1,472)	2,725	2,762
Restricted cash	245	210
Deferred income taxes	0	91
Investments in affiliates and other, less allowance for credit losses (2023—$38; 2022—$21)	1,391	1,373
Total other assets	8,888	8,963
Total assets	71,104	67,358
Current liabilities:
Accounts payable	3,835	3,395
Accrued salaries and benefits	2,940	1,971
Advance ticket sales	6,704	7,555
Frequent flyer deferred revenue	3,095	2,693
Current maturities of long-term debt	4,018	2,911
Current maturities of other financial liabilities	57	23
Current maturities of operating leases	576	561
Current maturities of finance leases	172	104
Other	806	779
Total current liabilities	22,203	19,992
Long-term debt	25,057	28,283
Long-term obligations under operating leases	4,503	4,459
Long-term obligations under finance leases	91	115
Other liabilities and deferred credits:
Frequent flyer deferred revenue	4,048	3,982
Pension liability	968	747
Postretirement benefit liability	637	671
Deferred income taxes	594	0
Other financial liabilities	2,265	844
Other	1,414	1,369
Total other liabilities and deferred credits	9,926	7,613
Commitments and contingencies
Stockholders' equity:
Preferred stock	0	0
Common stock at par, $0.01 par value; authorized 1,000,000,000 shares; outstanding 328,018,739 and 326,930,321 shares at December 31, 2023 and 2022, respectively	4	4
Additional capital invested	8,992	8,986
Stock held in treasury, at cost	(3,441)	(3,534)
Retained earnings	3,831	1,265
Accumulated other comprehensive income	(62)	175
Total stockholders' equity	9,324	6,896
Total liabilities and stockholders' equity	$ 71,104	$ 67,358

Statements of Consolidated Stockholders' Equity (UA) - USD ($) $ in Millions	Total	United Airlines, Inc.	Additional Capital Invested	Additional Capital Invested United Airlines, Inc.	Retained Earnings	Retained Earnings United Airlines, Inc.	Accumulated Other Comprehensive Income (Loss)	Accumulated Other Comprehensive Income (Loss) United Airlines, Inc.	(Receivable from) Payable to Related Parties, Net United Airlines, Inc.
Balance at Dec. 31, 2020	$ 5,960	$ 5,928	$ 8,366	$ 85	$ 2,626	$ 4,939	$ (1,139)	$ (1,139)	$ 2,043
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(1,964)	(1,962)			(1,964)	(1,962)
Other comprehensive income (loss)	197	197					197	197
Stock-settled share-based compensation	232	232	232	232
Impact of UAL common stock issuance	532	532	532						532
Other		71							71
Balance at Dec. 31, 2021	5,029	4,998	9,156	317	625	2,977	(942)	(942)	2,646
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	737	739			737	739
Other comprehensive income (loss)	1,117	1,117					1,117	1,117
Stock-settled share-based compensation	86	86	86	86
Other		(75)							(75)
Balance at Dec. 31, 2022	6,896	6,865	8,986	403	1,265	3,716	175	175	2,571
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	2,618	2,620			2,618	2,620
Other comprehensive income (loss)	(237)	(237)					(237)	(237)
Stock-settled share-based compensation	77	77	77	77
Other		(31)		2					(33)
Balance at Dec. 31, 2023	$ 9,324	$ 9,294	$ 8,992	$ 482	$ 3,831	$ 6,336	$ (62)	$ (62)	$ 2,538

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(g)(1)(ii))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480678/235-10-S99-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 323
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481687/323-10-50-3

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 825
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 28
-Subparagraph (f)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482907/825-10-50-28

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 220
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482765/220-10-50-6

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 250
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483443/250-10-50-3

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 250
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (b)(2)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483443/250-10-50-1

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 815
-SubTopic 40
-Name Accounting Standards Codification
-Section 65
-Paragraph 1
-Subparagraph (f)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480175/815-40-65-1

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 250
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 8
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483443/250-10-50-8

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 250
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 9
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483443/250-10-50-9

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 250
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 11
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483443/250-10-50-11

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 250
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 11
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483443/250-10-50-11

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Topic 250
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 4
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483443/250-10-50-4

Reference 13: http://www.xbrl.org/2003/role/exampleRef
-Topic 946
-SubTopic 830
-Name Accounting Standards Codification
-Section 55
-Paragraph 10
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480167/946-830-55-10

Reference 14: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 220
-Name Accounting Standards Codification
-Section 45
-Paragraph 7
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483581/946-220-45-7

Reference 15: http://www.xbrl.org/2003/role/disclosureRef
-Topic 944
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04(18))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483586/944-220-S99-1

Reference 16: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 22
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-22

Reference 17: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.6-07(9))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483575/946-220-S99-1

Reference 18: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 3
-Subparagraph (SX 210.6-09(1)(d))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483575/946-220-S99-3

Reference 19: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1A
-Subparagraph (SX 210.13-01(a)(4)(i))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480097/470-10-S99-1A

Reference 20: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 470
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1A
-Subparagraph (SX 210.13-01(a)(4)(ii))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480097/470-10-S99-1A

Reference 21: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1A
-Subparagraph (SX 210.13-01(a)(4)(iii)(A))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480097/470-10-S99-1A

Reference 22: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1A
-Subparagraph (SX 210.13-01(a)(4)(iv))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480097/470-10-S99-1A

Reference 23: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1A
-Subparagraph (SX 210.13-01(a)(5))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480097/470-10-S99-1A

Reference 24: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1B
-Subparagraph (SX 210.13-02(a)(4)(i))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480097/470-10-S99-1B

Reference 25: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1B
-Subparagraph (SX 210.13-02(a)(4)(iii)(A))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480097/470-10-S99-1B

Reference 26: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1B
-Subparagraph (SX 210.13-02(a)(4)(iii)(B))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480097/470-10-S99-1B

Reference 27: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1B
-Subparagraph (SX 210.13-02(a)(4)(iv))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480097/470-10-S99-1B

Reference 28: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1B
-Subparagraph (SX 210.13-02(a)(5))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480097/470-10-S99-1B

Reference 29: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 30
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-30

Reference 30: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 32
-Subparagraph (f)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-32

Reference 31: http://www.xbrl.org/2003/role/disclosureRef
-Topic 260
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 60B
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482689/260-10-45-60B

Reference 32: http://www.xbrl.org/2003/role/exampleRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 31
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-31

Reference 33: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 32
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-32

Reference 34: http://www.xbrl.org/2003/role/disclosureRef
-Topic 205
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 7
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483499/205-20-50-7

Reference 35: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 230
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 28
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482740/230-10-45-28

Reference 36: http://www.xbrl.org/2003/role/disclosureRef
-Topic 220
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 1A
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482790/220-10-45-1A

Reference 37: http://www.xbrl.org/2003/role/disclosureRef
-Topic 220
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 1B
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482790/220-10-45-1B

Reference 38: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 220
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03(20))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483621/220-10-S99-2

Reference 39: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 942
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04(22))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483589/942-220-S99-1

+ Details

- Definition

Amount after tax and reclassification adjustments of other comprehensive income (loss).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-SubTopic 10
-Topic 505
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-2

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 830
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481674/830-30-50-1

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 830
-SubTopic 30
-Name Accounting Standards Codification
-Section 45
-Paragraph 17
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481694/830-30-45-17

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 944
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04(19))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483586/944-220-S99-1

Reference 5: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 220
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 4
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482765/220-10-50-4

Reference 6: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 220
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482765/220-10-50-5

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 830
-SubTopic 30
-Name Accounting Standards Codification
-Section 45
-Paragraph 20
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481694/830-30-45-20

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 220
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03(21))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483621/220-10-S99-2

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 942
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04(23))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483589/942-220-S99-1

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 220
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 1B
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482790/220-10-45-1B

Reference 11: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Section 55
-Paragraph 15
-SubTopic 10
-Topic 220
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482739/220-10-55-15

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Topic 220
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 1A
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482790/220-10-45-1A

+ Details

- Definition

Equity impact of the value of new stock issued during the period. Includes shares issued in an initial public offering or a secondary public offering.

+ References + Details

- Definition

Amount of equity (deficit) attributable to parent. Excludes temporary equity and equity attributable to noncontrolling interest.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 852
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 10
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481372/852-10-55-10

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Topic 946
-SubTopic 830
-Name Accounting Standards Codification
-Section 55
-Paragraph 12
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480167/946-830-55-12

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 210
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.6-04(19))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479617/946-210-S99-1

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 210
-Name Accounting Standards Codification
-Section S99
-Paragraph 2
-Subparagraph (SX 210.6-05(4))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479617/946-210-S99-2

Reference 5: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 946
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 3
-Subparagraph (SX 210.6-09(4)(b))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483575/946-220-S99-3

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 3
-Subparagraph (SX 210.6-09(6))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483575/946-220-S99-3

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 3
-Subparagraph (SX 210.6-09(7))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483575/946-220-S99-3

Reference 8: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(g)(1)(ii))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480678/235-10-S99-1

Reference 9: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 323
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481687/323-10-50-3

Reference 10: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 825
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 28
-Subparagraph (f)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482907/825-10-50-28

Reference 11: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(29))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480566/210-10-S99-1

Reference 12: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(31))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480566/210-10-S99-1

Reference 13: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(30))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480566/210-10-S99-1

Reference 14: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 2
-Subparagraph (SAB Topic 4.E)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480418/310-10-S99-2

+ Details

Leases and Capacity Purchase Agreements - Additional Information Related to Leases (Details)	Dec. 31, 2023	Dec. 31, 2022
Leases [Abstract]
Weighted-average remaining lease term - operating leases	10 years	10 years
Weighted-average remaining lease term - finance leases	2 years	3 years
Weighted-average remaining lease term - other financial liabilities	10 years	9 years
Weighted-average discount rate - operating leases	5.80%	5.50%
Weighted-average discount rate - finance leases	6.30%	6.40%
Weighted-average interest rate - other financial liabilities	5.30%	6.00%

Special Charges (Credits) - Components of Special Charges (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Operating:
Labor contract ratification bonuses	$ 814	$ 0	$ 0
CARES Act grant	0	0	(4,021)
Severance and benefit costs	0	0	438
Impairment of assets	0	0	97
(Gains) losses on sale of assets and other special charges	135	140	119
Total operating special charges (credits)	949	140	(3,367)
Nonoperating unrealized (gains) losses on investments, net	(27)	(20)	34
Nonoperating debt extinguishment and modification fees	11	7	50
Nonoperating special termination benefits and settlement losses	0	0	31
Total nonoperating special charges and unrealized (gains) losses on investments, net	(16)	(13)	115
Total operating and nonoperating special charges (credits) and unrealized (gains) losses on investments, net	933	127	(3,252)
Income tax expense (benefit), net of valuation allowance	(214)	(33)	728
Total operating and nonoperating special charges (credits) and unrealized (gains) losses on investments, net of income taxes	$ 719	$ 94	$ (2,524)

Leases and Capacity Purchase Agreements - Summary of Scheduled Future Minimum Lease Payments under Operating and Finance Leases (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Operating Leases
2024	$ 813
2025	726
2026	706
2027	885
2028	685
After 2028	2,942
Minimum lease payments	6,757
Imputed interest	(1,678)
Present value of minimum lease payments	5,079
Less: current maturities of lease obligations	(576)	$ (561)
Long-term lease obligations	4,503	4,459
Finance Leases
2024	183
2025	60
2026	19
2027	9
2028	8
After 2028	5
Minimum lease payments	284
Imputed interest	(21)
Present value of minimum lease payments	263
Less: current maturities of lease obligations	(172)	(104)
Long-term lease obligations	$ 91	$ 115

Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2023

Accounting Policies [Abstract]

Use of Estimates

Use of Estimates—The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America ("GAAP") requires management to make estimates and assumptions that affect the amounts reported in these financial statements and accompanying notes. Actual results could differ from those estimates.

Revenue Recognition

Revenue Recognition—Passenger revenue is recognized when transportation is provided and Cargo revenue is recognized when shipments arrive at their destination. Other operating revenue is recognized as the related performance obligations are satisfied.

Passenger tickets and related ancillary services sold by the Company for flights are purchased primarily via credit card transactions, with payments collected by the Company in advance of the performance of related services. The Company initially records ticket sales in its Advance ticket sales liability, deferring revenue recognition until the travel occurs. For travel that has more than one flight segment, the Company deems each segment as a separate performance obligation and recognizes revenue for each segment as travel occurs. Tickets sold by other airlines where the Company provides the transportation are recognized as passenger revenue at the estimated value to be billed to the other airline when travel is provided. Differences between amounts billed and the actual amounts may be rejected and rebilled or written off if the amount recorded was different from the original estimate. When necessary, the Company records a reserve against its billings and payables with other airlines based on historical experience.

The Company sells certain tickets with connecting flights with one or more segments operated by its other airline partners. For segments operated by its other airline partners, the Company has determined that it is acting as an agent on behalf of the other airlines as they are responsible for their portion of the contract (i.e. transportation of the passenger). The Company, as the agent, recognizes revenue within Other operating revenue at the time of the travel for the net amount representing commission to be retained by the Company for any segments flown by other airlines.

Refundable tickets expire after one year from the date of issuance. Non-refundable tickets generally expire on the date of the intended travel, unless the date is extended by notification from the customer on or before the intended travel date.

United initially capitalizes the costs of selling airline travel tickets and then recognizes those costs as Distribution expense at the time of travel. Costs to sell a ticket include credit card fees, travel agency and other commissions paid, as well as global distribution systems booking fees.

Advance Ticket Sales. Advance ticket sales represent the Company's liability to provide air transportation in the future. All tickets sold at any given point in time have travel dates through the next 12 months. The Company defers amounts related to future travel in its Advance ticket sales liability account.

The Company estimates the value of Advance ticket sales that will expire unused ("breakage") and recognizes revenue and any changes in estimates in proportion to the usage of the related tickets. To determine breakage, the Company uses its historical experience with expired tickets and certificates and other facts, such as recent aging trends, program changes and modifications that could affect the ultimate expiration patterns.

In the years ended December 31, 2023, 2022 and 2021, the Company recognized approximately $5.7 billion, $3.3 billion and $1.8 billion, respectively, of passenger revenue for tickets that were included in Advance ticket sales at the beginning of those periods.

Revenue by Geography. The Company further disaggregates revenue by geographic regions. The Company deploys its aircraft across its route network through a single route scheduling system to maximize its value. When making resource allocation decisions, the Company's chief operating decision maker evaluates flight profitability data, which considers aircraft type and route economics. The Company's chief operating decision maker makes resource allocation decisions to maximize the Company's consolidated financial results. Operating segments are defined as components of an enterprise with separate financial information, which are evaluated regularly by the chief operating decision maker and are used in resource allocation and performance assessments. Managing the Company as one segment allows management the opportunity to maximize the value of its route network.

The Company attributes revenue among the geographic areas based upon the origin and destination of each flight segment. The Company's operations involve an insignificant level of revenue-producing assets in geographic regions as the overwhelming majority of the Company's revenue-producing assets (primarily U.S. registered aircraft) can be deployed in any of its geographic regions.

Ticket Taxes

Ticket Taxes—Certain governmental taxes are imposed on the Company's ticket sales through a fee included in ticket prices. The Company collects these fees and remits them to the appropriate government agency. These fees are recorded on a net basis and, as a result, are excluded from revenue.

Frequent Flyer Accounting

Frequent Flyer Accounting—United's MileagePlus loyalty program builds customer loyalty by offering awards, benefits and services to program participants. Members in this program earn miles for travel on United, United Express, Star Alliance members and certain other airlines that participate in the program. Members can also earn miles by purchasing goods and services from our network of non-airline partners. We have contracts to sell miles to these partners with the terms extending from one to six years. These partners include domestic and international credit card issuers, retail merchants, hotels, car rental companies and our participating airline partners. Miles can be redeemed for free (other than taxes and government-imposed fees), discounted or upgraded air travel and non-travel awards.

Miles Earned in Conjunction with Travel. When frequent flyers earn miles for flights, the Company recognizes a portion of the ticket sales as revenue when the travel occurs and defers a portion of the ticket sale representing the value of the related miles as a separate performance obligation. The Company determines the estimated selling price of travel and miles as if each element is sold on a separate basis. The total consideration from each ticket sale is then allocated to each of these elements, individually, on a pro-rata basis. At the time of travel, the Company records the portion allocated to the miles to Frequent flyer deferred revenue on the Company's consolidated balance sheet and subsequently recognizes it into revenue when miles are redeemed for air travel and non-air travel awards.

Estimated Selling Price of Miles. The Company's estimated selling price of miles is based on an equivalent ticket value, which incorporates the expected redemption of miles, as the best estimate of selling price for these miles. The equivalent ticket value is based on the prior 12 months' weighted average equivalent ticket value of similar fares as those used to settle award redemptions while taking into consideration such factors as redemption pattern, cabin class, loyalty status and geographic region. The estimated selling price of miles is adjusted by breakage that considers a number of factors, including redemption patterns of various customer groups.

Estimate of Miles Not Expected to be Redeemed ("Breakage"). The Company's breakage model is based on the assumption that the likelihood that an account will redeem its miles can be estimated based on a consideration of the account's historical behavior. The Company uses a logit regression model to estimate the probability that an account will redeem its current miles balance. The Company reviews its breakage estimates annually based upon the latest available information. The Company's estimate of the expected breakage of miles requires management judgment and current and future changes to breakage assumptions, or to program rules and program redemption opportunities, may result in material changes to the deferred revenue balance as well as recognized revenues from the program. For the portion of the outstanding miles that we estimate will not be redeemed, we recognize the associated value proportionally as the remaining miles are redeemed.

Co-Brand Agreement. United has a contract (the "Co-Brand Agreement") to sell MileagePlus miles to its co-branded credit card partner JPMorgan Chase Bank USA, N.A. ("Chase"). Chase awards miles to MileagePlus members based on their credit card activity. United identified the following significant separately identifiable performance obligations in the Co-Brand Agreement:

•MileagePlus miles awarded – United has a performance obligation to provide MileagePlus cardholders with miles to be used for air travel and non-travel award redemptions. The Company records Passenger revenue related to the travel awards when the transportation is provided and records Other revenue related to the non-travel awards when the goods or services are delivered. The Company records the cost associated with non-travel awards in Other operating revenue, as an agent.

•Marketing – United has a performance obligation to provide Chase access to United's customer list and the use of United's brand. Marketing revenue is recorded to Other operating revenue as miles are delivered to Chase.

•Advertising – United has a performance obligation to provide advertising in support of the MileagePlus card in various customer contact points such as United's website, email promotions, direct mail campaigns, airport advertising and in-flight advertising. Advertising revenue is recorded to Other operating revenue as miles are delivered to Chase.

•Other travel-related benefits – United's performance obligations are comprised of various items such as waived bag fees, seat upgrades and lounge passes. Lounge passes are recorded to Other operating revenue as customers use the lounge passes. Bag fees and seat upgrades are recorded to Passenger revenue at the time of the associated travel.

We account for all the payments received under the Co-Brand Agreement by allocating them to the separately identifiable performance obligations. The fair value of the separately identifiable performance obligations is determined using management's estimated selling price of each component. The objective of using the estimated selling price based methodology is to determine the price at which we would transact a sale if the product or service were sold on a stand-alone basis. Accordingly, we determine our best estimate of selling price by considering multiple inputs and methods including, but not limited to, discounted cash flows, brand value, volume discounts, published selling prices, number of miles awarded and number of miles redeemed. The Company estimated the selling prices and volumes over the term of the Co-Brand Agreement, at the inception of the contract, in order to determine the allocation of proceeds to each of the components to be delivered. We also evaluate volumes on an annual basis, which may result in a change in the allocation of the estimated consideration from the Co-Brand Agreement on a prospective basis.

Frequent Flyer Deferred Revenue. Miles in MileagePlus members' accounts are combined into one homogeneous pool and are thus not separately identifiable, for award redemption purposes, between miles earned in the current period and those in their beginning balance. Of the miles expected to be redeemed, the Company expects the majority of these miles to be redeemed within two years. The current portion of the Frequent flyer deferred revenue is based on expected redemptions in the next 12 months.

Cash and Cash Equivalents and Restricted Cash

Cash and Cash Equivalents and Restricted Cash—Highly liquid investments with a maturity of three months or less on their acquisition date are classified as cash and cash equivalents. Restricted cash is classified as short-term or long-term in the consolidated balance sheets based on the expected timing of return of the assets to the Company or payment to an outside party.

Restricted cash-current—The December 31, 2023 balance includes amounts to be used for the payment of principal, interest and fees on the $4.8 billion of senior secured notes and a secured term loan facility (the "MileagePlus Financing") secured by substantially all of the assets of Mileage Plus Holdings, LLC ("MPH"), a direct wholly-owned subsidiary of United.

Restricted cash-non-current—The December 31, 2023 balance primarily includes collateral associated with the MileagePlus Financing, collateral for letters of credit and collateral associated with facility leases and other insurance-related obligations.

Investments

Investments—Highly liquid investments with maturities of greater than three months to a year, at the time of purchase, are classified as short-term investments and are stated at fair value. Investments with maturities beyond one year when purchased are classified as short-term investments if they are expected to be available to support our short-term liquidity needs. Our short-term investments in debt securities are classified as available-for-sale and are stated at fair value. Realized gains and losses on sales of these investments are reflected in Miscellaneous, net in the consolidated statements of operations. Unrealized gains and losses on available-for-sale debt securities are reflected as a component of accumulated other comprehensive income (loss). Equity investments are accounted for under the equity method if we are able to exercise significant influence over an investee. Equity investments for which we do not have significant influence are recorded at fair value or at cost, if fair value is not readily determinable, with adjustments for observable changes in price or impairments (referred to as the measurement alternative). Changes in fair value are recorded in Unrealized gains (losses) on investments, net in the consolidated statements of operations. See Note 8 of this report for additional information related to investments.

Compensation received in connection with purchase agreements

Compensation received in connection with purchase agreements—The Company accounts for compensation received from vendors as deferred credits that will generally be recognized as a reduction to the cost of the asset received in future periods.

Accounts Receivable

Accounts Receivable—Accounts receivable primarily consist of amounts due from credit card companies, non-airline partners, and cargo customers. We provide an allowance for credit losses expected to be incurred. We base our allowance on various factors including, but not limited to, aging, payment history, write-offs, macro-economic indicators and other credit monitoring indicators.

Aircraft Fuel, Spare Parts and Supplies

Aircraft Fuel, Spare Parts and Supplies—The Company accounts for aircraft fuel, spare parts and supplies at average cost and provides an obsolescence allowance for aircraft spare parts with an assumed residual value of 10% of original cost.

Property and Equipment

Property and Equipment—The Company records additions to owned operating property and equipment at cost when acquired. Property under finance leases and the related obligation for future lease payments are recorded at an amount equal to the initial present value of those lease payments. Modifications that enhance the operating performance or extend the useful lives of airframes or engines are capitalized as property and equipment. We periodically receive credits in connection with the acquisition of aircraft and engines including those related to contractual damages related to delays in delivery. These credits are deferred until the aircraft and engines are delivered and then applied as a reduction to the cost of the related equipment.Depreciation and amortization of owned depreciable assets is based on the straight-line method over the assets' estimated useful lives. Leasehold improvements are amortized over the remaining term of the lease, including estimated facility renewal options when renewal is reasonably certain at key airports, or the estimated useful life of the related asset, whichever is less. Properties under finance leases are amortized using the straight-line method over the life of the lease or, in the case of certain aircraft, over their estimated useful lives, whichever is shorter. Amortization of finance lease assets is included in depreciation and amortization expense.

Long-Lived Asset Impairments

Long-Lived Asset Impairments—The Company evaluates the carrying value of long-lived assets subject to amortization whenever events or changes in circumstances indicate that an impairment may exist. For purposes of this testing, the Company has generally identified the aircraft fleet type as the lowest level of identifiable cash flows for its mainline fleet and the contract level for its regional fleet under capacity purchase agreements ("CPAs"). An impairment charge is recognized when the asset's carrying value exceeds its net undiscounted future cash flows. The amount of the charge is the difference between the asset's carrying value and fair market value.

Intangibles

Intangibles—The Company has finite-lived and indefinite-lived intangible assets, including goodwill. Finite-lived intangible assets are amortized over their estimated useful lives. Goodwill and indefinite-lived intangible assets are not amortized but are reviewed for impairment on an annual basis as of October 1, or more frequently if events or circumstances indicate that the asset may be impaired. When there is a triggering event, the Company typically determines fair value using either market or a variation of the income approach valuation techniques. These

measurements include the following key assumptions: (1) forecasted revenues, expenses, margin and cash flows, (2) terminal period growth rate, (3) an estimated weighted average cost of capital, (4) asset-specific risk factor and (5) a tax rate. These assumptions are consistent with those that hypothetical market participants would use. Because we are required to make estimates and assumptions when evaluating goodwill and indefinite-lived intangible assets for impairment, actual results may differ materially from these estimates. We recognize an impairment when the fair value of an intangible asset is less than its carrying value.

Every year, the Company evaluates its intangible assets for possible impairments. For the Company's China route authority, the Company performed a quantitative assessment which involved determining the fair value of the asset and comparing that amount to the asset's carrying value. For all other intangible assets, the Company performed a qualitative assessment of whether it was more likely than not that an impairment had occurred. To determine fair value of the China route authority, the Company used a discounted cash flow method. Key inputs into the models included forecasted revenues, fuel costs, other operating costs, margin and an overall discount rate. These assumptions are inherently uncertain as they relate to future events and circumstances.

Labor Costs

Labor Costs—The Company records expenses associated with new or amendable labor agreements when the amounts are probable and estimable. These could include costs associated with retro-active lump sum cash payments made in conjunction with the ratification of labor agreements. To the extent these upfront costs are in lieu of future pay increases, they would be capitalized and amortized over the term of the labor agreements. If not, these amounts would be expensed.

Share-Based Compensation

Share-Based Compensation—The Company measures the cost of employee services received in exchange for an award of equity instruments based on the grant date fair value of the award. The resulting cost is recognized over the period during which an employee is required to provide service in exchange for the award, usually the vesting period. Obligations for cash-settled restricted stock units ("RSUs") are remeasured at fair value throughout the requisite service period at the close of the reporting period based upon UAL's stock price. In addition to the service requirement, certain RSUs have performance metrics that must be achieved prior to vesting. These awards are accrued based on the expected level of achievement at each reporting period. An adjustment is recorded each reporting period to adjust compensation expense based on the then current level of expected performance achievement for the performance-based awards. See Note 4 of this report for additional information on UAL's share-based compensation plans.

Maintenance and Repairs

Maintenance and Repairs—The cost of maintenance and repairs, including the cost of minor replacements, is charged to expense as incurred, except for costs incurred under our power-by-the-hour ("PBTH") engine maintenance agreements. PBTH contracts transfer certain risk to third-party service providers and fix the amount we pay per flight hour or per cycle to the service provider in exchange for maintenance and repairs under a predefined maintenance program. Under PBTH agreements, the Company recognizes expense at a level rate per engine hour, unless the level of service effort and the related payments during the period are substantially consistent, in which case the Company recognizes expense based on the amounts paid.

Advertising

Advertising—Advertising costs, which are included in Other operating expenses, are expensed as incurred.

Third-Party Business

Third-Party Business—The Company has third-party business activity that includes ground handling, maintenance services, flight academy and frequent flyer award non-travel redemptions. Third-party business revenue is recorded in Other operating revenue. Expenses associated with these third-party business activities are recorded in Other operating expenses, except for non-travel mileage redemption. Non-travel mileage redemption expenses are recorded to Other operating revenue.

Uncertain Income Tax Positions

Uncertain Income Tax Positions—The Company has recorded reserves for income taxes and associated interest that may become payable in future years. Although management believes that its positions taken on income tax matters are reasonable, the Company nevertheless established tax and interest reserves in recognition that various taxing authorities may challenge certain of the positions taken by the Company, potentially resulting in additional liabilities for taxes and interest. The Company's uncertain tax position reserves are reviewed periodically and are adjusted as events occur that affect its estimates, such as the availability of new information, the lapsing of applicable statutes of limitation, the conclusion of tax audits, the measurement of additional estimated liability, the identification of new tax matters, the release of administrative tax guidance affecting its estimates of tax liabilities, or the rendering of relevant court decisions. The Company records penalties and interest relating to uncertain tax positions as part of income tax expense in its consolidated statements of operations.

Recently Issued Accounting Standards

Recently Issued Accounting Standards— In June 2022, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") No. 2022-03, Fair Value Measurement (Topic 820): Fair Value Measurement of Equity Securities Subject to Contractual Sale Restrictions. Under this standard, a contractual restriction on the sale of an equity security is not considered in measuring the security's fair value. The standard also requires certain disclosures for equity securities that are subject to contractual sale restrictions. The ASU became effective January 1, 2024. We do not expect this ASU to have a material impact on the valuation of our equity investments; however, we may be required to include additional disclosures to the extent we have material equity investments subject to contractual sale restrictions.

Fair Value Information

Accounting standards require us to use valuation techniques to measure fair value that maximize the use of observable inputs and minimize the use of unobservable inputs. These inputs are prioritized as follows:

Level 1

Unadjusted quoted prices in active markets for assets or liabilities identical to those to be reported at fair value

Level 2

Other inputs that are observable directly or indirectly, such as quoted prices for similar assets or liabilities or market-corroborated inputs

Level 3

Unobservable inputs for which there is little or no market data and which require us to develop our own assumptions about how market participants would price the assets or liabilities

Assets and liabilities measured at fair value are based on the valuation techniques identified in the tables below. The valuation techniques are as follows:

(a) Market approach. Prices and other relevant information generated by market transactions involving identical or comparable assets and liabilities; and

(b) Income approach. Techniques to convert future amounts to a single current value based on market expectations (including present value techniques, option-pricing and excess earnings models).

Special Charges (Credits) - Narrative (Details) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2021 USD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($) aircraft employee
Special Charges [Line Items]
Labor contract ratification bonuses		$ 814,000	$ 0	$ 0
Gain on sale of assets and other special charges		(135,000)	(140,000)	(119,000)
Nonoperating unrealized gains (losses)		27,000	20,000	(34,000)
Deferred Debt Issuance Cost, Writeoff		11,000
Loss contingency, loss in period			94,000
Loss contingency contract disputes			23,000
Extinguishment of debt, amount			7,000	50,000
Cash received under the payroll support program				5,800,000
Proceeds from the issuance of an unsecured loan				1,700,000
Severance and benefit costs		0	0	438,000
Impairment of assets		0	0	$ 97,000
Number of aircraft and spare engines retired \| aircraft				64
Gain (loss) on net charges				$ (119,000)
Airbus A319 & Boeing 737-700
Special Charges [Line Items]
Impairment of assets				$ 61,000
Airbus A319
Special Charges [Line Items]
Number of aircraft held for sale \| aircraft				13
Boeing 737-700
Special Charges [Line Items]
Number of aircraft held for sale \| aircraft				13
Embraer EMB 145LR
Special Charges [Line Items]
Impairment of assets				$ 36,000
Employee Separation \| Voluntary Separation Leave Programs
Special Charges [Line Items]
Number of employees electing to voluntarily separate from the company \| employee				4,500
Special termination benefits				$ 31,000
Employee Separation \| Voluntary Separation Leave Programs \| Full-Time Employees
Special Charges [Line Items]
Restructuring programs, one-time contribution per employee	$ 125			125
Employee Separation \| Voluntary Separation Leave Programs \| Part-Time Employees
Special Charges [Line Items]
Restructuring programs, one-time contribution per employee	$ 75			75
Payroll Support Program 2 & 3 (PSP 2 & 3) Warrants
Special Charges [Line Items]
Proceeds from issuance of warrants				99,000
Payroll Support Program 2 and 3 (PSP 2 & 3) Note
Special Charges [Line Items]
Grant income				$ 4,000,000
Unsecured Debt
Special Charges [Line Items]
Prepayment of term loan facility		$ 1,000,000
Long term debt			$ 400,000
Fixed interest rate			4.25%

Income Taxes - Income Tax Provision (Benefit) Differed from Amounts Computed at the Statutory Federal Income Tax Rate and Significant Components (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Income Tax Disclosure [Abstract]
Income tax provision (benefit) at statutory rate	$ 711	$ 208	$ (537)
State income tax provision (benefit), net of federal income tax benefit	46	13	(34)
Nondeductible employee meals	15	12	7
Nondeductible transportation fringe benefit	13	10	8
Valuation allowance	(21)	(10)	(38)
Other, net	5	20	1
Income tax expense (benefit)	769	253	(593)
Current	13	5	(10)
Deferred	$ 756	$ 248	$ (583)

Significant Accounting Policies - Narrative (Details) $ in Millions	12 Months Ended
	Dec. 31, 2023 USD ($) segment	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
Summary Of Significant Accounting Policies [Line Items]
Expiration period for refundable tickets	1 year
Expiration period for advance ticket sales	12 months
Number of operating segments \| segment	1
Revenue	$ 53,717	$ 44,955	$ 24,634
Period over which miles are expected to be redeemed	two years
Senior secured notes	$ 4,800
Carrying value of computer software	453	471
Impairment, long-lived asset			$ 97
Impairment, Long-Lived Asset, Held-for-Use, Statement of Income or Comprehensive Income [Extensible Enumeration]			Restructuring, Settlement and Impairment Provisions
Amortization expense	37	41	$ 49
Projected amortization expense in 2024	32
Projected amortization expense in 2025	28
Projected amortization expense in 2026	18
Projected amortization expense in 2027	11
Projected amortization expense in 2028	10
Advertising expense	$ 221	165	99
Minimum
Summary Of Significant Accounting Policies [Line Items]
Term for frequent flyer mileage sales to partners	1 year
Maximum
Summary Of Significant Accounting Policies [Line Items]
Term for frequent flyer mileage sales to partners	6 years
Computer software
Summary Of Significant Accounting Policies [Line Items]
Depreciation expense	$ 168	166	182
Advance Ticket Sales
Summary Of Significant Accounting Policies [Line Items]
Revenue recognized	5,700	3,300	1,800
Ancillary Fees Recorded within Passenger Revenues
Summary Of Significant Accounting Policies [Line Items]
Revenue	4,100	3,400	2,200
Other Operating Revenue
Summary Of Significant Accounting Policies [Line Items]
Revenue	3,176	2,752	2,088
Other Operating Revenue \| Chase and Other Partner Agreements
Summary Of Significant Accounting Policies [Line Items]
Revenue	$ 2,700	$ 2,400	$ 1,800

Common Stockholders' Equity and Preferred Securities - Summary of Warrants Outstanding (Details) shares in Millions	Dec. 31, 2023 $ / shares shares
Class of Warrant or Right [Line Items]
Number of Shares of UAL Common Stock (in shares)	10.0
PSP1 Warrants
Class of Warrant or Right [Line Items]
Number of Shares of UAL Common Stock (in shares)	4.8
Exercise Price (in dollars per share) \| $ / shares	$ 31.50
CARES Act Warrants
Class of Warrant or Right [Line Items]
Number of Shares of UAL Common Stock (in shares)	1.7
Exercise Price (in dollars per share) \| $ / shares	$ 31.50
PSP2 Warrants
Class of Warrant or Right [Line Items]
Number of Shares of UAL Common Stock (in shares)	2.0
Exercise Price (in dollars per share) \| $ / shares	$ 43.26
PSP3 Warrants
Class of Warrant or Right [Line Items]
Number of Shares of UAL Common Stock (in shares)	1.5
Exercise Price (in dollars per share) \| $ / shares	$ 53.92

Commitments and Contingencies - Narrative (Details) technician in Thousands		1 Months Ended	4 Months Ended	12 Months Ended
	May 01, 2023 USD ($)	Sep. 30, 2023	Dec. 31, 2023 USD ($) employee	Dec. 31, 2023 USD ($) employee option	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	May 31, 2023 employee contract	Jan. 31, 2023 technician
Commitments and Contingencies [Line Items]
Gross capital expenditures				$ 7,171,000,000	$ 4,819,000,000	$ 2,107,000,000
Loss contingency, loss in period					94,000,000
Aggregate balance			$ 3,243,000,000	$ 3,243,000,000
Number of call options to purchase regional jet aircraft \| option				252
IAM National Pension Plan
Commitments and Contingencies [Line Items]
Number of employees \| employee							30,000
Number of contracts ratified \| contract							5
Payment for ratification of contracts and taxes	$ 48,000,000
Air Line Pilots Association
Commitments and Contingencies [Line Items]
Agreement in principle pay rate increase period		4 years
Expenses associated with AIP			$ 765,000,000
United Airlines, Inc.
Commitments and Contingencies [Line Items]
Gross capital expenditures				$ 7,171,000,000	$ 4,819,000,000	$ 2,107,000,000
Number of employees \| employee			103,300	103,300
Percentage of employees represented by various U.S. labor organizations				83.00%
Number of technicians \| technician								8
Surety Bonds \| United Airlines, Inc.
Commitments and Contingencies [Line Items]
Contingent liabilities based on participation			$ 429,000,000	$ 429,000,000
Tax-Exempt Special Facilities Revenue Bonds
Commitments and Contingencies [Line Items]
Underlying debt and interest			1,900,000,000	1,900,000,000
Tax-Exempt Special Facilities Revenue Bonds \| Indirect Guarantee of Indebtedness
Commitments and Contingencies [Line Items]
Underlying debt and interest			447,000,000	447,000,000
Contingent liabilities based on participation			2,500,000,000	2,500,000,000
Aircraft Mortgage Debt
Commitments and Contingencies [Line Items]
Underlying debt and interest			77,000,000	77,000,000
Floating Rate Debt
Commitments and Contingencies [Line Items]
Long term debt			11,300,000,000	$ 11,300,000,000
Debt instrument, remaining terms				12 years
Loans And Leases From Non U S Entities
Commitments and Contingencies [Line Items]
Debt instrument, remaining terms				12 years
Aggregate balance			$ 8,100,000,000	$ 8,100,000,000

Share-Based Compensation Plans - Summary of Unearned Compensation and Weighted-Average Remaining Period to Recognize Costs (Details) $ in Millions	12 Months Ended
	Dec. 31, 2023 USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unearned Compensation	$ 81
RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unearned Compensation	$ 78
Weighted-Average Remaining Period (in years)	1 year 4 months 24 days
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unearned Compensation	$ 3
Weighted-Average Remaining Period (in years)	2 years 8 months 12 days

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 35
-Paragraph 1D
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480483/718-10-35-1D

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 35
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480483/718-10-35-3

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)(1)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)(2)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)(3)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(i)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(ii)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(iii)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(iv)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(iv)(01)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(iv)(02)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(iv)(03)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(iv)(04)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 14: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(2)(i)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 15: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(2)(ii)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 16: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(2)(iii)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 17: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(2)(iii)(01)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 18: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(2)(iii)(02)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 19: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(2)(iii)(03)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 20: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (d)(1)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 21: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (d)(2)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 22: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (e)(1)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 23: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (e)(2)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 24: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (f)(2)(i)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 25: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (f)(2)(ii)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 26: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (f)(2)(iii)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 27: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (f)(2)(iv)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 28: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (f)(2)(v)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

+ Details

Schedule II - Valuation and Qualifying Accounts (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Allowance for credit losses - receivables:
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	$ 11	$ 28	$ 78
Additions Charged to Costs and Expenses	27	22	3
Deductions	23	39	53
Other	3	0	0
Balance at End of Period	18	11	28
Allowance for credit losses - receivables: \| United Airlines, Inc.
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	11	28	78
Additions Charged to Costs and Expenses	27	22	3
Deductions	23	39	53
Other	3	0	0
Balance at End of Period	18	11	28
Obsolescence allowance—spare parts:
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	610	546	478
Additions Charged to Costs and Expenses	102	73	79
Deductions	23	9	11
Other	0	0	0
Balance at End of Period	689	610	546
Obsolescence allowance—spare parts: \| United Airlines, Inc.
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	610	546	478
Additions Charged to Costs and Expenses	102	73	79
Deductions	23	9	11
Other	0	0	0
Balance at End of Period	689	610	546
Allowance for credit losses - investments in affiliates and other:
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	21	622	522
Additions Charged to Costs and Expenses	20	20	1
Deductions	0	539	0
Other	(3)	(82)	99
Balance at End of Period	38	21	622
Allowance for credit losses - investments in affiliates and other: \| United Airlines, Inc.
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	21	622	522
Additions Charged to Costs and Expenses	20	20	1
Deductions	0	539	0
Other	(3)	(82)	99
Balance at End of Period	38	21	622
Valuation allowance for deferred tax assets:
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	199	210	247
Additions Charged to Costs and Expenses	(21)	(10)	(38)
Deductions	0	0	0
Other	1	(1)	1
Balance at End of Period	179	199	210
Valuation allowance for deferred tax assets: \| United Airlines, Inc.
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	199	210	247
Additions Charged to Costs and Expenses	(21)	(10)	(38)
Deductions	0	0	0
Other	1	(1)	1
Balance at End of Period	$ 179	$ 199	$ 210

Pension, Postretirement And Other Employee Benefit Plans - Participation in the IAM National Pension Plan (Details) - IAM National Pension Plan - Pension Benefits - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Jan. 01, 2021
Multiemployer Plans [Line Items]
Plan length	10 years
Additional contribution as a percentage of the hourly contribution rate	2.50%
Surcharge imposed	No
United Airlines, Inc.
Multiemployer Plans [Line Items]
Funded percentage				87.10%
Contributions	$ 87	$ 75	$ 58

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 715
-SubTopic 80
-Name Accounting Standards Codification
-Section 55
-Paragraph 8
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480547/715-80-55-8

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Topic 715
-SubTopic 80
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480576/715-80-50-6

Reference 3: http://www.xbrl.org/2003/role/exampleRef
-Topic 715
-SubTopic 80
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480576/715-80-50-6

Reference 4: http://www.xbrl.org/2003/role/exampleRef
-Topic 715
-SubTopic 80
-Name Accounting Standards Codification
-Section 50
-Paragraph 11
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480576/715-80-50-11

Reference 5: http://www.xbrl.org/2003/role/exampleRef
-Topic 715
-SubTopic 80
-Name Accounting Standards Codification
-Section 50
-Paragraph 11
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480576/715-80-50-11

Reference 6: http://www.xbrl.org/2003/role/exampleRef
-Topic 715
-SubTopic 80
-Name Accounting Standards Codification
-Section 50
-Paragraph 11
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480576/715-80-50-11

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 80
-Name Accounting Standards Codification
-Section 35
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480606/715-80-35-1

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 80
-Name Accounting Standards Codification
-Section 50
-Paragraph 11
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480576/715-80-50-11

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 80
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480576/715-80-50-5

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 80
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480576/715-80-50-5

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 80
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480576/715-80-50-5

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 80
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480576/715-80-50-5

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 80
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Subparagraph (e)(1)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480576/715-80-50-5

Reference 14: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 80
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Subparagraph (e)(2)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480576/715-80-50-5

Reference 15: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 80
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Subparagraph (f)(1)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480576/715-80-50-5

Reference 16: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 80
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Subparagraph (f)(2)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480576/715-80-50-5

Reference 17: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 80
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Subparagraph (f)(3)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480576/715-80-50-5

Reference 18: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 80
-Name Accounting Standards Codification
-Section 50
-Paragraph 9
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480576/715-80-50-9

Reference 19: http://www.xbrl.org/2003/role/exampleRef
-Topic 715
-SubTopic 80
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480576/715-80-50-6

+ Details

Accumulated Other Comprehensive Income (Loss) (Tables)

12 Months Ended

Dec. 31, 2023

Equity [Abstract]

Components of Accumulated Other Comprehensive Income, Net of Tax

The tables below present the components of the Company's AOCI, net of tax (in millions):


	Pension and Other Postretirement Liabilities			Investments and Other		Deferred Taxes (a)		Total
Balance at December 31, 2020	$	(1,102)		$	2	$	(39)	$	(1,139)
Change in value	239			(2)		(53)		184
Amounts reclassified to earnings	16		(b)	—		(3)		13
Balance at December 31, 2021	(847)			—		(95)		(942)
Change in value	1,474			(35)		(321)		1,118
Amounts reclassified to earnings	(1)		(b)	—		—		(1)
Balance at December 31, 2022	626			(35)		(416)		175
Change in value	(199)			31		38		(130)
Amounts reclassified to earnings	(138)		(b)	—		31		(107)
Balance at December 31, 2023	$	289		$	(4)	$	(347)	$	(62)

(a)Includes approximately $285 million of deferred income tax expense that will not be recognized in net income until the related pension and postretirement benefit obligations are fully extinguished. We consider all income sources, including other comprehensive income, in determining the amount of tax benefit allocated to results from operations. (b)This AOCI component is included in the computation of net periodic pension and other postretirement costs, specifically the following components: amortization of unrecognized (gain) loss, amortization of prior service credit and other. See Note 7 of this report for additional information on pensions and other postretirement liabilities.

Income Taxes - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
Income Taxes - Narrative (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Income Taxes [Line Items]
Capital loss carryforwards, valuation allowance	$ 150
Unrecognized tax benefits	66	$ 58	$ 55
Federal
Income Taxes [Line Items]
Tax credits	50
Federal \| United Airlines, Inc.
Income Taxes [Line Items]
NOL carryforwards	12,000
Tax effected amount of NOLs	2,500
NOLs without an expiration date	$ 11,600
Federal \| Minimum
Income Taxes [Line Items]
Tax credit expiration period	1 year
Federal \| Maximum
Income Taxes [Line Items]
Tax credit expiration period	20 years
Federal \| 2029 \| United Airlines, Inc.
Income Taxes [Line Items]
NOL carryforwards	$ 200
Federal \| 2033 \| United Airlines, Inc.
Income Taxes [Line Items]
NOL carryforwards	200
State
Income Taxes [Line Items]
Tax credits	56
NOL and tax credit carryforwards, valuation allowance	29
State \| United Airlines, Inc.
Income Taxes [Line Items]
NOL carryforwards	3,400
Tax effected amount of NOLs	$ 200
State \| Minimum
Income Taxes [Line Items]
Tax credit expiration period	1 year
State \| Minimum \| United Airlines, Inc.
Income Taxes [Line Items]
NOL expiration period	1 year
State \| Maximum
Income Taxes [Line Items]
Tax credit expiration period	15 years
State \| Maximum \| United Airlines, Inc.
Income Taxes [Line Items]
NOL expiration period	20 years

Accumulated Other Comprehensive Income (Loss) - Components of the Company's AOCI (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, deferred taxes	$ (416)	$ (95)	$ (39)
Balance	6,896	5,029	5,960
Change in value, deferred tax	38	(321)	(53)
Change in value	(130)	1,118	184
Amounts reclassified to earnings, deferred taxes	31	0	(3)
Amounts reclassified to earnings	(107)	(1)	13
Balance, deferred taxes	(347)	(416)	(95)
Balance	9,324	6,896	5,029
Accumulated Other Comprehensive Income (Loss)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance	175	(942)	(1,139)
Balance	(62)	175	(942)
Deferred income taxes	285
Pension and Other Postretirement Liabilities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, before tax	626	(847)	(1,102)
Change in value, before tax	(199)	1,474	239
Amounts reclassified to earnings, before tax	(138)	(1)	16
Balance, before tax	289	626	(847)
Investments and Other
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, before tax	(35)	0	2
Change in value, before tax	31	(35)	(2)
Amounts reclassified to earnings, before tax	0	0	0
Balance, before tax	$ (4)	$ (35)	$ 0

Share-Based Compensation Plans - Narrative (Details) - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of RSUs and restricted stock vested in period	$ 76	$ 274	$ 104
RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards granted (in shares)	2.6
Number of days used to compute performance period average closing price of restricted stock units	20 days
Liabilities related to share based payments	$ 3
Payment related to share-based liabilities	$ 3	$ 7	$ 29
Time-Vested RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards granted (in shares)	2.0
Performance-Based RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards granted (in shares)	0.6
Award vesting period	3 years

Overview	12 Months Ended
Overview	Dec. 31, 2023
Unusual or Infrequent Items, or Both [Abstract]
Overview	Overview United Airlines Holdings, Inc. (together with its consolidated subsidiaries, "UAL" or the "Company") is a holding company and its wholly-owned subsidiary is United Airlines, Inc. (together with its consolidated subsidiaries, "United"). As UAL consolidates United for financial statement purposes, disclosures that relate to activities of United also apply to UAL, unless otherwise noted. United's operating revenues and operating expenses comprise nearly 100% of UAL's revenues and operating expenses. In addition, United comprises approximately the entire balance of UAL's assets, liabilities and operating cash flows. When appropriate, UAL and United are named specifically for their individual contractual obligations and related disclosures and any significant differences between the operations and results of UAL and United are separately disclosed and explained. We sometimes use the words "we," "our," "us," and the "Company" in this report for disclosures that relate to all of UAL and United.

Special Charges (Credits) (Tables)

12 Months Ended

Dec. 31, 2023

Restructuring and Related Activities [Abstract]

Components of Special Charges

For the years ended December 31, operating and nonoperating special charges (credits) and unrealized (gains) losses on investments in the statements of consolidated operations consisted of the following (in millions):


Operating:	2023		2022		2021
Labor contract ratification bonuses	$	814	$	—	$	—
CARES Act grant	—		—		(4,021)
Severance and benefit costs	—		—		438
Impairment of assets	—		—		97
(Gains) losses on sale of assets and other special charges	135		140		119
Total operating special charges (credits)	949		140		(3,367)
Nonoperating unrealized (gains) losses on investments, net	(27)		(20)		34
Nonoperating debt extinguishment and modification fees	11		7		50
Nonoperating special termination benefits and settlement losses	—		—		31
Total nonoperating special charges and unrealized (gains) losses on investments, net	(16)		(13)		115
Total operating and nonoperating special charges (credits) and unrealized (gains) losses on investments, net	933		127		(3,252)
Income tax expense (benefit), net of valuation allowance	(214)		(33)		728
Total operating and nonoperating special charges (credits) and unrealized (gains) losses on investments, net of income taxes	$	719	$	94	$	(2,524)

Pension, Postretirement And Other Employee Benefit Plans

12 Months Ended

Dec. 31, 2023

Retirement Benefits [Abstract]

PENSION, POSTRETIREMENT AND OTHER EMPLOYEE BENEFIT PLANS

The following summarizes the significant pension and other postretirement plans of United:

Pension Plans. United maintains two primary defined benefit pension plans, one covering certain pilot employees and another covering certain U.S. non-pilot employees. Each of these plans provide benefits based on a combination of years of benefit accruals service and an employee's final average compensation. Additional benefit accruals are frozen under the plan covering certain pilot employees and for management and administrative employees covered under the non-pilot plan. Benefit accruals for certain non-pilot employees continue. United maintains additional defined benefit pension plans, which cover certain international employees.

Other Postretirement Plans. United maintains postretirement medical programs which provide medical benefits to certain retirees and eligible dependents, as well as life insurance benefits to certain retirees participating in the plan. Benefits provided are subject to applicable contributions, co-payments, deductibles and other limits as described in the specific plan documentation.

In 2021, the Company offered several voluntary leave programs and voluntary separation programs ("Voluntary Programs") to certain eligible employees, which in some cases included a partially-paid leave of absence with active health benefits and travel privileges. Under these Voluntary Programs, employees generally separated from employment with certain post-employment health benefits and travel privileges. Included in the Voluntary Programs offered during the first quarter of 2021, the Company offered special separation benefits in the form of additional subsidies for retiree medical costs for certain U.S.-based front-line employees. The subsidies were in the form of a one-time contribution to a notional retiree health account of $125,000 for full-time employees and $75,000 for part-time employees. As a result, the Company recorded $31 million for those additional benefits in 2021.

Actuarial assumption changes are reflected as a component of the net actuarial (gain) loss. The 2023 actuarial losses were mainly related to a decrease in the discount rate applied at December 31, 2023 compared to December 31, 2022. Actuarial (gains) losses will be amortized over the average remaining service life of the covered active employees.


	Pension Benefits
	Year Ended December 31, 2023		Year Ended December 31, 2022
Accumulated benefit obligation:	$	3,910	$	3,596

Change in projected benefit obligation:
Projected benefit obligation at beginning of year	$	4,181	$	6,473
Service cost	124		204
Interest cost	217		188
Actuarial (gain) loss	204		(2,186)
Benefits paid	(177)		(464)
Other	1		(34)
Projected benefit obligation at end of year	$	4,550	$	4,181

Change in plan assets:
Fair value of plan assets at beginning of year	$	3,467	$	4,626
Actual income (loss) on plan assets	281		(678)
Employer contributions	22		8
Benefits paid	(177)		(464)
Other	6		(25)
Fair value of plan assets at end of year	$	3,599	$	3,467
Funded status—Net amount recognized	$	(951)	$	(714)


	Pension Benefits
	December 31, 2023		December 31, 2022
Amounts recognized in the consolidated balance sheets consist of:
Noncurrent asset	$	21	$	44
Current liability	(4)		(11)
Noncurrent liability	(968)		(747)
Total liability	$	(951)	$	(714)

Amounts recognized in accumulated other comprehensive income (loss) consist of:
Net actuarial loss	$	(242)	$	(77)
Prior service cost	—		(1)
Total accumulated other comprehensive loss	$	(242)	$	(78)


	Other Postretirement Benefits
	Year Ended December 31, 2023		Year Ended December 31, 2022
Change in benefit obligation:
Benefit obligation at beginning of year	$	788	$	1,129
Service cost	4		9
Interest cost	42		30
Plan participants' contributions	67		69
Benefits paid	(177)		(179)
Actuarial (gain) loss	22		(270)
Benefit obligation at end of year	$	746	$	788

Change in plan assets:
Fair value of plan assets at beginning of year	$	48	$	49
Actual return on plan assets	1		1
Employer contributions	107		108
Plan participants' contributions	67		69
Benefits paid	(177)		(179)
Fair value of plan assets at end of year	46		48
Funded status—Net amount recognized	$	(700)	$	(740)


	Other Postretirement Benefits
	December 31, 2023		December 31, 2022
Amounts recognized in the consolidated balance sheets consist of:
Current liability	$	(63)	$	(69)
Noncurrent liability	(637)		(671)
Total liability	$	(700)	$	(740)

Amounts recognized in accumulated other comprehensive income (loss) consist of:
Net actuarial gain	$	309	$	369
Prior service credit	222		335
Total accumulated other comprehensive income	$	531	$	704

The following information relates to all pension plans with an accumulated benefit obligation and a projected benefit obligation in excess of plan assets at December 31 (in millions):


	2023		2022
Projected benefit obligation	$	4,407	$	4,045
Accumulated benefit obligation	3,767		3,461
Fair value of plan assets	3,435		3,287

Net periodic benefit cost (credit) for the years ended December 31 included the following components (in millions):


	2023				2022				2021
	Pension Benefits		Other Postretirement Benefits		Pension Benefits		Other Postretirement Benefits		Pension Benefits		Other Postretirement Benefits
Service cost	$	124	$	4	$	204	$	9	$	239	$	10
Interest cost	217		42		188		30		184		25
Expected return on plan assets	(251)		(1)		(306)		(1)		(283)		(1)

Amortization of unrecognized actuarial (gain) loss	8		(38)		120		(14)		170		(28)
Amortization of prior service credits	1		(112)		—		(112)		—		(123)
Special termination benefits - Voluntary Programs	—		—		—		—		—		31
Curtailment	—		—		—		—		(8)		—
Other	3		—		5		—		5		—
Net periodic benefit cost (credit)	$	102	$	(105)	$	211	$	(88)	$	307	$	(86)

Service cost is recorded in Salaries and related costs on the statement of consolidated operations. All other components of net periodic benefit costs are recorded in Miscellaneous, net on the statement of consolidated operations.

The Company's expected Net periodic benefit cost (credit) for 2024 is as follows (in millions):


	Pension Benefits		Other Postretirement Benefits
Net periodic benefit cost (credit)	$	108	$	(78)

The assumptions used for the benefit plans were as follows:


	Pension Benefits
Assumptions used to determine benefit obligations	2023		2022
Discount rate	5.04	%	5.20	%
Rate of compensation increase	3.84	%	3.83	%

Assumptions used to determine net expense
Discount rate	5.20	%	2.90	%
Expected return on plan assets	7.53	%	7.16	%
Rate of compensation increase	3.83	%	3.83	%


	Other Postretirement Benefits
Assumptions used to determine benefit obligations	2023		2022
Discount rate	5.43	%	5.66	%

Assumptions used to determine net expense
Discount rate	5.66	%	2.82	%
Expected return on plan assets	3.00	%	3.00	%
Health care cost trend rate assumed for next year	7.00	%	5.60	%
Rate to which the cost trend rate is assumed to decline (ultimate trend rate in 2033)	4.50	%	4.50	%

The Company used the Society of Actuaries' PRI-2012 Private Retirement Plans Mortality Tables projected generationally using the Society of Actuaries' MP-2021 projection scale.

The Company selected the 2023 discount rate for substantially all of its plans by using a hypothetical portfolio of high-quality bonds at December 31, 2023 that would provide the necessary cash flows to match projected benefit payments.

We develop our expected long-term rate of return assumption for our defined benefit plans based on historical experience and by evaluating input from the trustee managing the plans' assets. Our expected long-term rate of return on plan assets for these plans is based on a target allocation of assets, which is based on our goal of earning the highest rate of return while maintaining risk at acceptable levels. The plans strive to have assets sufficiently diversified so that adverse or unexpected results from one security class will not have an unduly detrimental impact on the entire portfolio. Plan fiduciaries regularly review our actual asset allocation and the pension plans' investments are periodically rebalanced to our targeted allocation when considered appropriate. United's plan assets are allocated within the following guidelines:


	Percent of Total		Expected Long-Term Rate of Return
Equity securities	25-73	%	9	%
Fixed-income securities	14-53		8
Alternatives	3-27		8


The table below shows the impacts of a change in certain assumptions on the 2024 net periodic benefit cost and the benefit obligations at December 31, 2023 (in millions):
	Pension Benefits		Other Postretirement Benefits
Impact on Benefit Obligation at December 31, 2023
100 basis points decrease in the weighted average discount rate	$	858	$	48

Impact on 2024 Net Periodic Benefit Cost
100 basis points decrease in the weighted average discount rate (a)	$	96	$	—
100 basis points decrease in the expected long-term rate of return on plan assets	35		—
(a) In general, as discount rates increase, the impact of changes in discount rates decreases. Therefore, these sensitivities cannot be extrapolated for larger increases or decreases in the discount rate. In addition, benefit cost is affected by other factors including, but not limited to, investment performance, contributions, demographic experience and other assumption changes.

Level 1

Unadjusted quoted prices in active markets for assets or liabilities identical to those to be reported at fair value

Level 2

Other inputs that are observable directly or indirectly, such as quoted prices for similar assets or liabilities or market-corroborated inputs

Level 3

Unobservable inputs for which there is little or no market data and which require us to develop our own assumptions about how market participants would price the assets or liabilities

Assets and liabilities measured at fair value are based on the valuation techniques identified in the tables below. The valuation techniques are as follows:

(a) Market approach. Prices and other relevant information generated by market transactions involving identical or comparable assets and liabilities; and

(b) Income approach. Techniques to convert future amounts to a single current value based on market expectations (including present value techniques, option-pricing and excess earnings models).

The following tables present information about United's pension and other postretirement plan assets at December 31 (in millions):


	2023										2022
Pension Plan Assets:	Total		Level 1		Level 2		Level 3		Assets Measured at NAV(a)		Total		Level 1		Level 2		Level 3		Assets Measured at NAV(a)
Equity securities funds	$	1,265	$	74	$	3	$	134	$	1,054	$	1,183	$	58	$	26	$	114	$	985
Fixed-income securities	1,325		—		411		3		911		1,316		—		527		5		784
Alternatives	779		—		—		136		643		887		—		—		161		726
Other investments	230		13		87		3		127		81		6		16		5		54
Total	$	3,599	$	87	$	501	$	276	$	2,735	$	3,467	$	64	$	569	$	285	$	2,549
Other Postretirement Benefit Plan Assets:
Deposit administration fund	$	46	$	—	$	—	$	46	$	—	$	48	$	—	$	—	$	48	$	—

Equity and Fixed-Income. Equities include investments in both developed market and emerging market equity securities. Fixed-income includes primarily U.S. and non-U.S. government fixed-income securities and non-U.S. corporate fixed-income securities, as well as securitized debt securities.

Deposit Administration Fund. This investment is a stable value investment product structured to provide investment income.

Alternatives. Alternative investments consist primarily of investments in hedge funds, real estate and private equity interests.

Other investments. Other investments consist of primarily cash equivalents, as well as insurance contracts.

The following table presents reconciliation of United's benefit plan assets measured at fair value using unobservable inputs (Level 3) for the years ended December 31, 2023 and 2022 (in millions):


	2023		2022
Balance at beginning of year	$	333	$	435
Actual income (loss) on plan assets:
Sold during the year	(50)		34
Held at year end	55		(39)
Purchases, sales, issuances and settlements (net)	(16)		(97)
Balance at end of year	$	322	$	333

Funding requirements for tax-qualified defined benefit pension plans are determined by government regulations. The Company does not expect any minimum required contributions for 2024 for its tax-qualified defined benefit pension plans. The Company expects to make approximately $104 million in contributions to its other postretirement benefit plans in 2024.


	Pension		Other Postretirement
2024	$	268	$	112
2025	301		100
2026	323		88
2027	348		80
2028	373		74
Years 2029 – 2033	1,896		274

Defined Contribution Plans. United offers several defined contribution plans to its employees. Depending upon the employee group, employer contributions consist of matching contributions and/or non-elective employer contributions. United's employer contribution percentages to its primary 401(k) defined contribution plans vary from 1% to 16% of eligible earnings depending on the terms of each plan. United recorded expenses for its primary 401(k) defined contribution plans of $960 million, $756 million and $651 million in the years ended December 31, 2023, 2022 and 2021, respectively.

Multi-Employer Plans. United's participation in the IAM National Pension Plan ("IAM Plan") for the annual period ended December 31, 2023 is outlined in the table below. The risks of participating in these multi-employer plans are different from single-employer plans, as United may be subject to additional risks that others do not meet their obligations, which in certain circumstances could revert to United. The IAM Plan reported $533 million in employers' contributions for the year ended December 31, 2022. For 2022, the Company's contributions to the IAM Plan represented more than 5% of total contributions to the IAM Plan. The 2023 information is not available as the applicable Form 5500 is not final for the plan year.


Pension Fund			IAM National Pension Fund ("IAM Fund")
EIN/ Pension Plan Number			51-6031295 — 002
Pension Protection Act Zone Status (2023 and 2022)			Critical (2023 and 2022). A plan is in "critical" status if the funded percentage is less than 65 percent. On April 17, 2019, the IAM National Pension Fund Board of Trustees voluntarily elected for the IAM Fund to be in critical status effective for the plan year beginning January 1, 2019 to strengthen the IAM Fund's financial health. The IAM Fund's funded percentage was 87.1% as of January 1, 2022.
FIP/RP Status Pending/Implemented			A 10-year Rehabilitation Plan effective, January 1, 2022, was adopted on April 17, 2019 that requires the Company to make an additional contribution of 2.5% of the hourly contribution rate, compounded annually for the length of the Rehabilitation Plan, effective June 1, 2019.
United's Contributions			$87 million, $75 million and $58 million in the years ended December 31, 2023, 2022 and 2021, respectively.
Surcharge Imposed			No
Expiration Date of Collective Bargaining Agreement			N/A

Profit Sharing. Substantially all employees participate in profit sharing based on a percentage of pre-tax earnings, excluding special or non-recurring charges, profit sharing expense and share-based compensation. Profit sharing percentages range from 5% to 20% depending on the work group, and in some cases profit sharing percentages vary above and below certain pre-tax margin thresholds. As part of the new collective bargaining agreement with the Air Line Pilots Association ("ALPA"), the thresholds were lowered retroactive to January 1, 2023 for the pilot work group. Eligible U.S. co-workers in each participating work group receive a profit sharing payout using a formula based on the ratio of each qualified co-worker's annual eligible earnings to the eligible earnings of all qualified co-workers in all domestic work groups. Eligible non-U.S. co-workers receive profit sharing based on the calculation under the U.S. profit sharing plan for management and administrative employees. The Company recorded profit sharing and related payroll tax expense of $681 million and $133 million in 2023 and 2022, respectively. As a result of the pre-tax loss in 2021, no profit sharing was recorded. Profit sharing expense is recorded as a component of Salaries and related costs in the Company's statements of consolidated operations.

- Definition

The entire disclosure for retirement benefits.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 70
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480794/715-70-50-1

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 17
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480482/715-20-55-17

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (d)(iv)(03)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480506/715-20-50-1

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (d)(i)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480506/715-20-50-1

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (q)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480506/715-20-50-1

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (l)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480506/715-20-50-1

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-Name Accounting Standards Codification
-Publisher FASB
-URI https://asc.fasb.org//715/tableOfContent

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (d)(iii)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480506/715-20-50-1

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (o)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480506/715-20-50-1

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (p)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480506/715-20-50-1

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (r)(1)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480506/715-20-50-1

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (r)(2)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480506/715-20-50-1

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section S99
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480126/715-20-S99-2

Reference 14: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 60
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480266/715-60-50-3

+ Details

Statements of Consolidated Stockholders' Equity (UAH) - USD ($) $ in Millions	Total	Common Stock	Additional Capital Invested	Treasury Stock	Retained Earnings	Accumulated Other Comprehensive Income (Loss)
Balance (in shares) at Dec. 31, 2020		311,800,000
Balance at Dec. 31, 2020	$ 5,960	$ 4	$ 8,366	$ (3,897)	$ 2,626	$ (1,139)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(1,964)				(1,964)
Other comprehensive income (loss)	197					197
Stock-settled share-based compensation	232		232
Warrants issued	99		99
Issuance of common stock (in shares)		11,000,000.0
Issuance of common stock	532		532
Stock issued for share-based awards, net of shares withheld for tax (in shares)		1,000,000.0
Stock issued for share-based awards, net of shares withheld for tax	(27)		(73)	83	(37)
Balance (in shares) at Dec. 31, 2021		323,800,000
Balance at Dec. 31, 2021	5,029	$ 4	9,156	(3,814)	625	(942)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	737				737
Other comprehensive income (loss)	1,117					1,117
Stock-settled share-based compensation	86		86
Stock issued for share-based awards, net of shares withheld for tax (in shares)		3,100,000
Stock issued for share-based awards, net of shares withheld for tax	$ (73)		(256)	280	(97)
Balance (in shares) at Dec. 31, 2022	326,930,321	326,900,000
Balance at Dec. 31, 2022	$ 6,896	$ 4	8,986	(3,534)	1,265	175
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	2,618				2,618
Other comprehensive income (loss)	(237)					(237)
Stock-settled share-based compensation	77		77
Proceeds from exercise of stock options	1		1
Stock issued for share-based awards, net of shares withheld for tax (in shares)		1,100,000
Stock issued for share-based awards, net of shares withheld for tax	$ (31)		(72)	93	(52)
Balance (in shares) at Dec. 31, 2023	328,018,739	328,000,000.0
Balance at Dec. 31, 2023	$ 9,324	$ 4	$ 8,992	$ (3,441)	$ 3,831	$ (62)

Common Stockholders' Equity and Preferred Securities - Narrative (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Mar. 03, 2021
Class of Warrant or Right [Line Items]
Common stock reserved for future issuance (in shares)	4,800,000
Junior preferred stock outstanding (in shares)	2
Junior preferred stock par value per share (in dollars per share)	$ 0.01
Preferred stock authorized to issue (in shares)	250,000,000
2021 ATM Offering
Class of Warrant or Right [Line Items]
Number of shares issuable under Equity Distribution Agreement (up to) (in shares)				37,000,000
Sale of common stock (in shares)	0	0	4,000,000
Share price (in dollars per share)			$ 57.50
Proceeds from the issuance of common stock			$ 250

Common Stockholders' Equity and Preferred Securities (Tables)

12 Months Ended

Dec. 31, 2023

Equity [Abstract]

Summary of Warrants Outstanding

The Company issued warrants to the U.S. Treasury Department ("Treasury") pursuant to the payroll support program ("PSP"), including extensions, and the loan program established under the Coronavirus Aid, Relief, and Economic Security Act (the "CARES Act"). See Note 9 of this report for additional information about the unsecured promissory notes issued by the Company to Treasury under the PSP and related extensions. As of December 31, 2023, the Company had the following warrants outstanding:


Warrant Description	Number of Shares of UAL Common Stock (in millions)	Exercise Price		Expiration Dates
PSP1 Warrants	4.8	$	31.50	4/20/2025	—	9/30/2025
CARES Act Warrants	1.7	31.50		9/28/2025
PSP2 Warrants	2.0	43.26		1/15/2026	—	4/29/2026
PSP3 Warrants	1.5	53.92		4/29/2026	—	6/10/2026
Total	10.0

Fair Value Measurements, Investments and Notes Receivable - Fair Value of Financial Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - Measured on a Recurring Basis - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	$ 6,058	$ 7,166
Restricted cash - current	31	45
Restricted cash - non-current	245	210
Equity securities	177	189
U.S. government and agency notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	8,257	8,914
Asset-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	0	325
Certificates of deposit placed through an account registry service ("CDARS")
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	73	0
Corporate debt
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	0	9
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	6,058	7,166
Restricted cash - current	31	45
Restricted cash - non-current	245	210
Equity securities	177	189
Level 1 \| U.S. government and agency notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	0	0
Level 1 \| Asset-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	0	0
Level 1 \| Certificates of deposit placed through an account registry service ("CDARS")
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	0	0
Level 1 \| Corporate debt
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	0	0
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	0	0
Restricted cash - current	0	0
Restricted cash - non-current	0	0
Equity securities	0	0
Level 2 \| U.S. government and agency notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	8,257	8,914
Level 2 \| Asset-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	0	325
Level 2 \| Certificates of deposit placed through an account registry service ("CDARS")
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	73	0
Level 2 \| Corporate debt
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	0	9
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	0	0
Restricted cash - current	0	0
Restricted cash - non-current	0	0
Equity securities	0	0
Level 3 \| U.S. government and agency notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	0	0
Level 3 \| Asset-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	0	0
Level 3 \| Certificates of deposit placed through an account registry service ("CDARS")
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	0	0
Level 3 \| Corporate debt
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	$ 0	$ 0

Statements of Consolidated Operations (UA) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Operating revenue:
Total operating revenue	$ 53,717	$ 44,955	$ 24,634
Operating expense:
Salaries and related costs	14,787	11,466	9,566
Aircraft fuel	12,651	13,113	5,755
Landing fees and other rent	3,076	2,576	2,416
Aircraft maintenance materials and outside repairs	2,736	2,153	1,316
Depreciation and amortization	2,671	2,456	2,485
Regional capacity purchase	2,400	2,299	2,147
Distribution expenses	1,977	1,535	677
Aircraft rent	197	252	228
Special charges	949	140	(3,367)
Other operating expenses	8,062	6,628	4,433
Total operating expense	49,506	42,618	25,656
Operating income (loss)	4,211	2,337	(1,022)
Nonoperating income (expense):
Interest expense	(1,956)	(1,778)	(1,657)
Interest income	827	298	36
Interest capitalized	182	105	80
Unrealized gains (losses) on investments, net	27	20	(34)
Miscellaneous, net	96	8	40
Total nonoperating expense, net	(824)	(1,347)	(1,535)
Income (loss) before income taxes	3,387	990	(2,557)
Income tax expense (benefit)	769	253	(593)
Net income (loss)	2,618	737	(1,964)
United Airlines, Inc.
Operating revenue:
Total operating revenue	53,717	44,955	24,634
Operating expense:
Salaries and related costs	14,787	11,466	9,566
Aircraft fuel	12,651	13,113	5,755
Landing fees and other rent	3,076	2,576	2,416
Aircraft maintenance materials and outside repairs	2,736	2,153	1,316
Depreciation and amortization	2,671	2,456	2,485
Regional capacity purchase	2,400	2,299	2,147
Distribution expenses	1,977	1,535	677
Aircraft rent	197	252	228
Special charges	949	140	(3,367)
Other operating expenses	8,059	6,626	4,431
Total operating expense	49,503	42,616	25,654
Operating income (loss)	4,214	2,339	(1,020)
Nonoperating income (expense):
Interest expense	(1,956)	(1,778)	(1,657)
Interest income	827	298	36
Interest capitalized	182	105	80
Unrealized gains (losses) on investments, net	27	20	(34)
Miscellaneous, net	96	8	40
Total nonoperating expense, net	(824)	(1,347)	(1,535)
Income (loss) before income taxes	3,390	992	(2,555)
Income tax expense (benefit)	770	253	(593)
Net income (loss)	2,620	739	(1,962)
Passenger revenue
Operating revenue:
Total operating revenue	49,046	40,032	20,197
Passenger revenue \| United Airlines, Inc.
Operating revenue:
Total operating revenue	49,046	40,032	20,197
Cargo
Operating revenue:
Total operating revenue	1,495	2,171	2,349
Cargo \| United Airlines, Inc.
Operating revenue:
Total operating revenue	1,495	2,171	2,349
Other operating revenue
Operating revenue:
Total operating revenue	3,176	2,752	2,088
Other operating revenue \| United Airlines, Inc.
Operating revenue:
Total operating revenue	$ 3,176	$ 2,752	$ 2,088

Consolidated Balance Sheets (UA) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Current assets:
Cash and cash equivalents	$ 6,058	$ 7,166
Short-term investments	8,330	9,248
Restricted cash	31	45
Receivables, less allowance for credit losses (2023—$18; 2022—$11)	1,898	1,801
Aircraft fuel, spare parts and supplies, less obsolescence allowance (2023—$689; 2022—$610)	1,561	1,109
Prepaid expenses and other	609	689
Total current assets	18,487	20,058
Operating property and equipment:
Flight equipment	48,448	42,775
Other property and equipment	10,527	9,334
Purchase deposits for flight equipment	3,550	2,820
Total operating property and equipment	62,525	54,929
Less—Accumulated depreciation and amortization	(22,710)	(20,481)
Total operating property and equipment, net	39,815	34,448
Operating lease right-of-use assets	3,914	3,889
Other assets:
Goodwill	4,527	4,527
Intangibles, less accumulated amortization (2023—$1,495; 2022—$1,472)	2,725	2,762
Restricted cash	245	210
Deferred income taxes	0	91
Investments in affiliates and other, less allowance for credit losses (2023—$38; 2022—$21)	1,391	1,373
Total other assets	8,888	8,963
Total assets	71,104	67,358
Current liabilities:
Accounts payable	3,835	3,395
Accrued salaries and benefits	2,940	1,971
Advance ticket sales	6,704	7,555
Frequent flyer deferred revenue	3,095	2,693
Current maturities of long-term debt	4,018	2,911
Current maturities of other financial liabilities	57	23
Current maturities of operating leases	576	561
Current maturities of finance leases	172	104
Other	806	779
Total current liabilities	22,203	19,992
Long-term debt	25,057	28,283
Long-term obligations under operating leases	4,503	4,459
Long-term obligations under finance leases	91	115
Other liabilities and deferred credits:
Frequent flyer deferred revenue	4,048	3,982
Pension liability	968	747
Postretirement benefit liability	637	671
Deferred income taxes	594	0
Other financial liabilities	2,265	844
Other	1,414	1,369
Total other liabilities and deferred credits	9,926	7,613
Commitments and contingencies
Stockholders' equity:
Common stock at par, $0.01 par value; authorized 1,000 shares; issued and outstanding 1,000 shares at December 31, 2023 and 2022	4	4
Additional capital invested	8,992	8,986
Retained earnings	3,831	1,265
Accumulated other comprehensive income	(62)	175
Total stockholders' equity	9,324	6,896
Total liabilities and stockholders' equity	71,104	67,358
United Airlines, Inc.
Current assets:
Cash and cash equivalents	6,058	7,166
Short-term investments	8,330	9,248
Restricted cash	31	45
Receivables, less allowance for credit losses (2023—$18; 2022—$11)	1,898	1,801
Aircraft fuel, spare parts and supplies, less obsolescence allowance (2023—$689; 2022—$610)	1,561	1,109
Prepaid expenses and other	609	689
Total current assets	18,487	20,058
Operating property and equipment:
Flight equipment	48,448	42,775
Other property and equipment	10,527	9,334
Purchase deposits for flight equipment	3,550	2,820
Total operating property and equipment	62,525	54,929
Less—Accumulated depreciation and amortization	(22,710)	(20,481)
Total operating property and equipment, net	39,815	34,448
Operating lease right-of-use assets	3,914	3,889
Other assets:
Goodwill	4,527	4,527
Intangibles, less accumulated amortization (2023—$1,495; 2022—$1,472)	2,725	2,762
Restricted cash	245	210
Deferred income taxes	0	62
Investments in affiliates and other, less allowance for credit losses (2023—$38; 2022—$21)	1,391	1,373
Total other assets	8,888	8,934
Total assets	71,104	67,329
Current liabilities:
Accounts payable	3,835	3,395
Accrued salaries and benefits	2,940	1,971
Advance ticket sales	6,704	7,555
Frequent flyer deferred revenue	3,095	2,693
Current maturities of long-term debt	4,018	2,911
Current maturities of other financial liabilities	57	23
Current maturities of operating leases	576	561
Current maturities of finance leases	172	104
Other	808	781
Total current liabilities	22,205	19,994
Long-term debt	25,057	28,283
Long-term obligations under operating leases	4,503	4,459
Long-term obligations under finance leases	91	115
Other liabilities and deferred credits:
Frequent flyer deferred revenue	4,048	3,982
Pension liability	968	747
Postretirement benefit liability	637	671
Deferred income taxes	622	0
Other financial liabilities	2,265	844
Other	1,414	1,369
Total other liabilities and deferred credits	9,954	7,613
Commitments and contingencies
Stockholders' equity:
Common stock at par, $0.01 par value; authorized 1,000 shares; issued and outstanding 1,000 shares at December 31, 2023 and 2022	0	0
Additional capital invested	482	403
Retained earnings	6,336	3,716
Accumulated other comprehensive income	(62)	175
Payable to parent	2,538	2,571
Total stockholders' equity	9,294	6,865
Total liabilities and stockholders' equity	$ 71,104	$ 67,329

Variable Interest Entities ("VIE")	12 Months Ended
Variable Interest Entities ("VIE")	Dec. 31, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
VARIABLE INTEREST ENTITIES ("VIE")	VARIABLE INTEREST ENTITIES ("VIE") Variable interests are contractual, ownership or other monetary interests in an entity that change with fluctuations in the fair value of the entity's net assets exclusive of variable interests. A VIE can arise from items such as lease agreements, loan arrangements, guarantees or service contracts. An entity is a VIE if (a) the entity lacks sufficient equity or (b) the entity's equity holders lack power or the obligation and right as equity holders to absorb the entity's expected losses or to receive its expected residual returns. If an entity is determined to be a VIE, the entity must be consolidated by the primary beneficiary. The primary beneficiary is the holder of the variable interests that has the power to direct the activities of a VIE that (i) most significantly impact the VIE's economic performance and (ii) has the obligation to absorb losses of or the right to receive benefits from the VIE that could potentially be significant to the VIE. Therefore, the Company must identify which activities most significantly impact the VIE's economic performance and determine whether it, or another party, has the power to direct those activities. Airport Leases. United is the lessee of real property under long-term operating leases at a number of airports where we are also the guarantor of approximately $1.9 billion of tax-exempt special facilities revenue bonds and interest thereon as of December 31, 2023. These leases are typically with municipalities or other governmental entities, which are excluded from the consolidation requirements concerning a VIE. To the extent United's leases and related guarantees are with a separate legal entity other than a governmental entity, United is not the primary beneficiary because the lease terms are consistent with market terms at the inception of the lease and the lease does not include a residual value guarantee, fixed-price purchase option, or similar feature. See Note 12 of this report for more information regarding United's guarantee of the tax-exempt special facilities revenue bonds. EETCs. United evaluated whether the pass-through trusts formed for its EETC financings, treated as either debt or aircraft operating leases, are VIEs required to be consolidated by United under applicable accounting guidance, and determined that the pass-through trusts are VIEs. Based on United's analysis as described below, United determined that it does not have a variable interest in the pass-through trusts. The primary risk of the pass-through trusts is credit risk (i.e. the risk that United, the issuer of the equipment notes, may be unable to make its principal and interest payments). The primary purpose of the pass-through trust structure is to enhance the credit worthiness of United's debt obligation through certain bankruptcy protection provisions, a liquidity facility (in certain of the EETC structures) and improved loan-to-value ratios for more senior debt classes. These credit enhancements lower United's total borrowing cost. Pass-through trusts are established to receive principal and interest payments on the equipment notes purchased by the pass-through trusts from United and remit these proceeds to the pass-through trusts' certificate holders. United does not invest in or obtain a financial interest in the pass-through trusts. Rather, United has an obligation to make interest and principal payments on its equipment notes held by the pass-through trusts. United does not intend to have any voting or non-voting equity interest in the pass-through trusts or to absorb variability from the pass-through trusts. Based on this analysis, the Company determined that it is not required to consolidate the pass-through trusts. Mesa. United concluded that Mesa is a VIE as of December 31, 2023. United holds a variable interest in Mesa in the form of an approximately 10% equity interest and several loans to Mesa, but United is not the primary beneficiary because it does not have power to direct the activities that most significantly impact Mesa's economic performance.

Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2023

Accounting Policies [Abstract]

Operating Revenue by Principal Geographic Region

The Company's operating revenue by principal geographic region (as defined by the U.S. Department of Transportation) for the years ended December 31 is presented in the table below (in millions):


	2023		2022		2021
Domestic (U.S. and Canada)	$	32,400	$	28,474	$	16,845
Atlantic	10,982		9,072		3,414
Pacific	5,267		2,927		1,507
Latin America	5,068		4,482		2,868
Total	$	53,717	$	44,955	$	24,634

Roll Forward of Frequent Flyer Deferred Revenue

The table below presents a roll forward of Frequent flyer deferred revenue (in millions):


	Year Ended December 31,
	2023		2022
Total Frequent flyer deferred revenue - beginning balance	$	6,675	$	6,282
Total miles awarded	3,297		2,558
Travel miles redeemed	(2,723)		(2,079)
Non-travel miles redeemed	(106)		(86)
Total Frequent flyer deferred revenue - ending balance	$	7,143	$	6,675

Reconciliation of Cash, Cash Equivalents and Restricted Cash

The following table provides a reconciliation of cash, cash equivalents and restricted cash reported within the consolidated balance sheets that sum to the total of the same such amounts shown in the statements of consolidated cash flows (in millions):


	At December 31,
	2023		2022		2021
Current assets:
Cash and cash equivalents	$	6,058	$	7,166	$	18,283
Restricted cash	31		45		37
Other assets:
Restricted cash	245		210		213
Total cash, cash equivalents and restricted cash shown in the statement of consolidated cash flows	$	6,334	$	7,421	$	18,533

Reconciliation of Cash, Cash Equivalents and Restricted Cash


	At December 31,
	2023		2022		2021
Current assets:
Cash and cash equivalents	$	6,058	$	7,166	$	18,283
Restricted cash	31		45		37
Other assets:
Restricted cash	245		210		213
Total cash, cash equivalents and restricted cash shown in the statement of consolidated cash flows	$	6,334	$	7,421	$	18,533

Estimated Useful Lives of Property and Equipment

The estimated useful lives of property and equipment are as follows:


						Estimated Useful Life (in years)
Aircraft, spare engines and related rotable parts						25 to 30
Aircraft seats						10 to 15
Buildings						25 to 45
Other property and equipment						3 to 15
Computer software						5 to 15
Building improvements						1 to 40

Information about Goodwill and Other Intangible Assets

The following table presents information about the Company's goodwill and other intangible assets at December 31 (in millions):


	2023				2022
	Gross Carrying Amount		Accumulated Amortization		Gross Carrying Amount		Accumulated Amortization
Goodwill	$	4,527			$	4,527

Indefinite-lived intangible assets
China route authority	$	1,020			$	1,020
Airport slots	574				574
Tradenames and logos	593				593
Alliances	404				404
Total	$	2,591			$	2,591

Finite-lived intangible assets
Frequent flyer database	$	1,177	$	1,068	$	1,177	$	1,040
Hubs	145		131		145		124
Contracts	—		—		7		7
Other	307		296		314		301
Total	$	1,629	$	1,495	$	1,643	$	1,472

Debt - Contractual Principal Payments under Outstanding Long-Term Debt Agreements (Details) - UAL and United $ in Millions	Dec. 31, 2023 USD ($)
Debt Instrument [Line Items]
2024	$ 4,018
2025	3,452
2026	5,245
2027	2,475
2028	5,306
After 2028	8,856
Long-term debt	$ 29,352

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 835
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482900/835-30-50-1

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(f))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480678/235-10-S99-1

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 3
-Subparagraph (SX 210.12-04(a))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480678/235-10-S99-3

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1B
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481139/470-20-50-1B

Reference 5: http://www.xbrl.org/2003/role/exampleRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 69B
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481568/470-20-55-69B

Reference 6: http://www.xbrl.org/2003/role/exampleRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 69C
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481568/470-20-55-69C

Reference 7: http://www.xbrl.org/2003/role/exampleRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 69E
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481568/470-20-55-69E

Reference 8: http://www.xbrl.org/2003/role/exampleRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 69F
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481568/470-20-55-69F

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1B
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481139/470-20-50-1B

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1B
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481139/470-20-50-1B

Reference 11: http://www.xbrl.org/2003/role/exampleRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1B
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481139/470-20-50-1B

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1B
-Subparagraph (e)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481139/470-20-50-1B

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1B
-Subparagraph (f)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481139/470-20-50-1B

Reference 14: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1B
-Subparagraph (h)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481139/470-20-50-1B

Reference 15: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1D
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481139/470-20-50-1D

Reference 16: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1D
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481139/470-20-50-1D

Reference 17: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1D
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481139/470-20-50-1D

Reference 18: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1E
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481139/470-20-50-1E

Reference 19: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1E
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481139/470-20-50-1E

Reference 20: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1E
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481139/470-20-50-1E

Reference 21: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1F
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481139/470-20-50-1F

Reference 22: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1F
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481139/470-20-50-1F

Reference 23: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1F
-Subparagraph (b)(1)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481139/470-20-50-1F

Reference 24: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1F
-Subparagraph (b)(2)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481139/470-20-50-1F

Reference 25: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1I
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481139/470-20-50-1I

+ Details

- Definition

Amount, after deduction of unamortized premium (discount) and debt issuance cost, of long-term debt. Excludes lease obligation.

+ References + Details

Commitments and Contingencies (Tables)

12 Months Ended

Dec. 31, 2023

Commitments and Contingencies Disclosure [Abstract]

Firm Commitments and Options to Purchase Aircraft and Summary of Commitments

As of December 31, 2023, United had firm commitments to purchase aircraft from The Boeing Company ("Boeing") and Airbus S.A.S. ("Airbus") presented in the table below:


		Contractual Aircraft Deliveries			Expected Aircraft Deliveries (b)
Aircraft Type	Number of Firm Commitments (a)	2024	2025	After 2025	2024	2025	After 2025
787	150	8	18	124	7	18	125
737 MAX 8	43	43	—	—	37	6	—
737 MAX 9	34	34	—	—	19	15	—
737 MAX 10	277	80	71	126	—	(c)	(c)
A321neo	126	26	38	62	25	24	77
A321XLR	50	—	8	42	—	1	49
A350	45	—	—	45	—	—	45
(a)United also has options and purchase rights for additional aircraft. (b)Expected aircraft deliveries reflect adjustments communicated by Boeing and Airbus or estimated by United. (c)Due to the delay in the certification of the 737 MAX 10 aircraft, we are unable to accurately forecast the expected delivery period.

Summary of Commitments

The table below summarizes United's firm commitments as of December 31, 2023, which include aircraft and related spare engines, aircraft improvements and non-aircraft capital commitments. Aircraft commitments are based on contractual scheduled aircraft deliveries without any adjustments communicated by Boeing and Airbus or estimated by United.


(in billions)
2024	$	12.1
2025	7.9
2026	6.0
2027	4.5
2028	6.1
After 2028	23.5
	$	60.1

Common Stockholders' Equity and Preferred Securities

12 Months Ended

Dec. 31, 2023

Equity [Abstract]

COMMON STOCKHOLDERS' EQUITY AND PREFERRED SECURITIES


Warrant Description	Number of Shares of UAL Common Stock (in millions)	Exercise Price		Expiration Dates
PSP1 Warrants	4.8	$	31.50	4/20/2025	—	9/30/2025
CARES Act Warrants	1.7	31.50		9/28/2025
PSP2 Warrants	2.0	43.26		1/15/2026	—	4/29/2026
PSP3 Warrants	1.5	53.92		4/29/2026	—	6/10/2026
Total	10.0

As of December 31, 2023, approximately 4.8 million shares of UAL's common stock were reserved for future issuance related to the issuance of equity-based awards under the Company's incentive compensation plans.

As of December 31, 2023, UAL had two shares of junior preferred stock (par value $0.01 per share) outstanding. In addition, UAL is authorized to issue 250 million shares of preferred stock (without par value) under UAL's amended and restated certificate of incorporation.

On March 3, 2021, the Company entered into an equity distribution agreement (the "Distribution Agreement") with several financial institutions (collectively, the "Managers"), relating to the issuance and sale from time to time by UAL (the "2021 ATM Offering"), through the Managers, of up to 37 million shares of UAL common stock (the "2021 ATM Shares"). Sales of the 2021 ATM Shares under the Distribution Agreement were allowed to be made in any transactions that were deemed to be "at the market offerings" as defined in Rule 415 under the Securities Act of 1933, as amended. During 2021, approximately 4 million shares were sold in the 2021 ATM Offering at an average price of $57.50 per share, with net proceeds to the Company totaling approximately $250 million. No shares were sold in 2022 or 2023 under the 2021 ATM Offering, which expired in March 2023.

- Definition

The entire disclosure for equity.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-13

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (h)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-13

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 14
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-14

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 235
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481062/946-235-50-2

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 235
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481062/946-235-50-2

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 505
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481004/946-505-50-6

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 815
-SubTopic 40
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480237/815-40-50-6

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480008/505-10-S99-1

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(e)(1))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480678/235-10-S99-1

Reference 10: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 505
-Name Accounting Standards Codification
-Publisher FASB
-URI https://asc.fasb.org//505/tableOfContent

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-13

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (g)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-13

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (i)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-13

Reference 14: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 14
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-14

Reference 15: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 14
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-14

Reference 16: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 16
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-16

Reference 17: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 18
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-18

Reference 18: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 18
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-18

Reference 19: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 18
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-18

+ Details

Variable Interest Entities ("VIE") (Details) $ in Billions	12 Months Ended
Variable Interest Entities ("VIE") (Details) $ in Billions	Dec. 31, 2023 USD ($)
Mesa
Variable Interest Entity [Line Items]
Ownership stake	10.00%
Tax-Exempt Special Facilities Revenue Bonds
Variable Interest Entity [Line Items]
Underlying debt and interest	$ 1.9

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References + Details

Leases and Capacity Purchase Agreements (Tables)

12 Months Ended

Dec. 31, 2023

Leases [Abstract]

Components of Lease Cost

The Company's lease cost for the years ended December 31 included the following components (in millions):


	2023		2022		2021
Operating lease cost	$	925	$	941	$	958
Variable and short-term lease cost	3,028		2,603		2,291
Amortization of finance lease assets	52		72		89
Interest on finance lease liabilities	20		13		16
Sublease income	(39)		(33)		(26)
Total lease cost	$	3,986	$	3,596	$	3,328

Summary of Scheduled Future Minimum Lease Payments under Operating Leases

The table below summarizes the Company's scheduled future minimum lease payments under operating and finance leases, recorded on the balance sheet, as of December 31, 2023 (in millions):


	Operating Leases		Finance Leases
2024	$	813	$	183
2025	726		60
2026	706		19
2027	885		9
2028	685		8
After 2028	2,942		5
Minimum lease payments	6,757		284
Imputed interest	(1,678)		(21)
Present value of minimum lease payments	5,079		263
Less: current maturities of lease obligations	(576)		(172)
Long-term lease obligations	$	4,503	$	91

Summary of Scheduled Future Minimum Lease Payments Under Finance Leases

The table below summarizes the Company's scheduled future minimum lease payments under operating and finance leases, recorded on the balance sheet, as of December 31, 2023 (in millions):


	Operating Leases		Finance Leases
2024	$	813	$	183
2025	726		60
2026	706		19
2027	885		9
2028	685		8
After 2028	2,942		5
Minimum lease payments	6,757		284
Imputed interest	(1,678)		(21)
Present value of minimum lease payments	5,079		263
Less: current maturities of lease obligations	(576)		(172)
Long-term lease obligations	$	4,503	$	91

Contractual Obligation, Fiscal Year Maturity

The table below presents the Company's contractual payments at December 31, 2023 under then-outstanding sale and leaseback agreements, for transactions that did not qualify as a sale under ASC Topic 606, in each of the next five calendar years (in millions):


	Other Financial Liabilities
2024	$	178
2025	178
2026	178
2027	472
2028	147
After 2028	2,090
	3,243
Imputed interest	(921)
Current maturities of other financial liabilities	(57)
Other financial liabilities	$	2,265

Additional Information Related to Leases

The table below presents additional information related to our leases as of December 31:


	2023		2022
Weighted-average remaining lease term - operating leases	10 years		10 years
Weighted-average remaining lease term - finance leases	2 years		3 years
Weighted-average remaining lease term - other financial liabilities	10 years		9 years
Weighted-average discount rate - operating leases	5.8	%	5.5	%
Weighted-average discount rate - finance leases	6.3	%	6.4	%
Weighted-average interest rate - other financial liabilities	5.3	%	6.0	%

Supplemental Cash Flow Information Related to Leases

The table below presents supplemental cash flow information related to leases during the year ended December 31 (in millions):


	2023		2022		2021
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows for operating leases	$	874	$	919	$	977
Operating cash flows for finance leases	21		13		18
Financing cash flows for finance leases	311		124		216

Future Lease Payment Under Terms of Capacity Purchase Agreement

Based on these assumptions as of December 31, 2023, our estimated future payments through the end of the terms of our CPAs are presented in the table below (in billions):


2024	$	2.4
2025	2.1
2026	2.1
2027	1.6
2028	1.3
After 2028	4.1
	$	13.6

Income Taxes - Temporary Differences and Carryforwards Giving Rise to Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Deferred income tax asset (liability):
Federal and state net operating loss ("NOL") carryforwards	$ 2,644	$ 2,932
Deferred revenue	1,845	1,783
Employee benefits, including pension, postretirement and medical	695	606
Operating lease liabilities	1,134	1,118
Other financial liabilities	414	141
Interest expense carryforward	579	510
Other	575	576
Less: Valuation allowance	(179)	(199)
Total deferred tax assets	7,707	7,467
Depreciation	(6,782)	(5,844)
Operating lease right-of-use asset	(887)	(881)
Intangibles	(632)	(651)
Total deferred tax liabilities	(8,301)	(7,376)
Net deferred tax liability	(594)
Net deferred tax asset		91
United Airlines, Inc.
Deferred income tax asset (liability):
Federal and state net operating loss ("NOL") carryforwards	2,616	2,903
Deferred revenue	1,845	1,783
Employee benefits, including pension, postretirement and medical	695	606
Operating lease liabilities	1,134	1,118
Other financial liabilities	414	141
Interest expense carryforward	579	510
Other	575	576
Less: Valuation allowance	(179)	(199)
Total deferred tax assets	7,679	7,438
Depreciation	(6,782)	(5,844)
Operating lease right-of-use asset	(887)	(881)
Intangibles	(632)	(651)
Total deferred tax liabilities	(8,301)	(7,376)
Net deferred tax liability	$ (622)
Net deferred tax asset		$ 62

Fair Value Measurements, Investments and Notes Receivable - Carrying Amounts and Estimated Fair Values of Financial Instruments (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Carrying Amount
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, carrying amount	$ 29,075	$ 31,194
Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	28,302	29,371
Fair Value \| Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	0	0
Fair Value \| Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	22,543	23,990
Fair Value \| Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	$ 5,759	$ 5,381

- Definition

Amount, after deduction of unamortized premium (discount) and debt issuance cost, of long-term debt. Excludes lease obligation.

+ References + Details

Audit Information	12 Months Ended
Audit Information	Dec. 31, 2023
Audit Information [Abstract]
Auditor Name	Ernst & Young LLP
Auditor Location	Chicago, Illinois
Auditor Firm ID	42

Earnings (Loss) Per Share

12 Months Ended

Dec. 31, 2023

Earnings Per Share [Abstract]

EARNINGS (LOSS) PER SHARE

The computations of UAL's basic and diluted earnings (loss) per share are set forth below for the years ended December 31 (in millions, except per share amounts):


	2023		2022		2021
Earnings (loss) available to common stockholders	$	2,618	$	737	$	(1,964)

Basic weighted-average shares outstanding	327.8		326.4		321.9
Dilutive effect of stock warrants (a)	2.2		1.5		—
Dilutive effect of employee stock awards	1.9		2.2		—
Diluted weighted-average shares outstanding	331.9		330.1		321.9

Earnings (loss) per share, basic	$	7.98	$	2.26	$	(6.10)
Earnings (loss) per share, diluted	$	7.89	$	2.23	$	(6.10)

Potentially dilutive securities (b)
Stock warrants (a)	1.5		3.5		0.9
Employee stock awards	0.6		0.7		0.7

(a) Represent warrants issued to Treasury pursuant to the payroll support program, including extensions, and the loan program established under the CARES Act. See Note 2 of this report for additional information about these warrants.

(b) Weighted-average potentially dilutive securities outstanding excluded from the computation of diluted earnings per share because the securities would have had an antidilutive effect.

Debt - Summary of Collateral Covenants and Cross Default Provisions (Details) - Line of Credit $ in Billions	Dec. 31, 2023 USD ($)
Credit Agreement
Debt Instrument [Line Items]
Unrestricted liquidity required for credit agreement	$ 2.0
Minimum ratio of appraised value of collateral for Credit Agreement	1.6
2026 Notes and 2029 Notes
Debt Instrument [Line Items]
Minimum ratio of appraised value of collateral for Credit Agreement	1.6
Additional interest required if minimum ratio is not met, percent	2.00%

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

+ Details

Pension, Postretirement And Other Employee Benefit Plans - Assumptions Used for Benefit Plans (Details)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Pension Benefits
Assumptions used to determine benefit obligations
Discount rate	5.04%	5.20%
Rate of compensation increase	3.84%	3.83%
Assumptions used to determine net expense
Discount rate	5.20%	2.90%
Expected return on plan assets	7.53%	7.16%
Rate of compensation increase	3.83%	3.83%
Other Postretirement Benefits
Assumptions used to determine benefit obligations
Discount rate	5.43%	5.66%
Assumptions used to determine net expense
Discount rate	5.66%	2.82%
Expected return on plan assets	3.00%	3.00%
Health care cost trend rate assumed for next year	7.00%	5.60%
Rate to which the cost trend rate is assumed to decline (ultimate trend rate in 2033)	4.50%	4.50%

Commitments and Contingencies - Firm Commitments and Options to Purchase Aircraft (Details)	Dec. 31, 2023 aircraft_commitment aircraft
787
Long-term Purchase Commitment [Line Items]
Number of Firm Commitments \| aircraft_commitment	150
Number Of Aircrafts Expected To Take Delivery [Abstract]
2024	8
2025	18
After 2025	124
2024	7
2025	18
After 2025	125
737 MAX 8
Long-term Purchase Commitment [Line Items]
Number of Firm Commitments \| aircraft_commitment	43
Number Of Aircrafts Expected To Take Delivery [Abstract]
2024	43
2025	0
After 2025	0
2024	37
2025	6
After 2025	0
737 MAX 9
Long-term Purchase Commitment [Line Items]
Number of Firm Commitments \| aircraft_commitment	34
Number Of Aircrafts Expected To Take Delivery [Abstract]
2024	34
2025	0
After 2025	0
2024	19
2025	15
After 2025	0
737 MAX 10
Long-term Purchase Commitment [Line Items]
Number of Firm Commitments \| aircraft_commitment	277
Number Of Aircrafts Expected To Take Delivery [Abstract]
2024	80
2025	71
After 2025	126
2024	0
A321neo
Long-term Purchase Commitment [Line Items]
Number of Firm Commitments \| aircraft_commitment	126
Number Of Aircrafts Expected To Take Delivery [Abstract]
2024	26
2025	38
After 2025	62
2024	25
2025	24
After 2025	77
A321XLR
Long-term Purchase Commitment [Line Items]
Number of Firm Commitments \| aircraft_commitment	50
Number Of Aircrafts Expected To Take Delivery [Abstract]
2024	0
2025	8
After 2025	42
2024	0
2025	1
After 2025	49
A350
Long-term Purchase Commitment [Line Items]
Number of Firm Commitments \| aircraft_commitment	45
Number Of Aircrafts Expected To Take Delivery [Abstract]
2024	0
2025	0
After 2025	45
2024	0
2025	0
After 2025	45

Leases and Capacity Purchase Agreements

12 Months Ended

Dec. 31, 2023

Leases [Abstract]

LEASES AND CAPACITY PURCHASE AGREEMENTS

United leases aircraft, airport passenger terminal space, aircraft hangars and related maintenance facilities, cargo terminals, other airport facilities, other commercial real estate, office and computer equipment and vehicles, among other items. Certain of these leases include provisions for variable lease payments which are based on several factors, including, but not limited to, relative leased square footage, available seat miles, enplaned passengers, passenger facility charges, terminal equipment usage fees, departures, and airports' annual operating budgets. Due to the variable nature of the rates, these leases are not recorded on our balance sheet as a right-of-use asset and lease liability.

For leases with terms greater than 12 months, we record the related right-of-use asset and lease liability at the present value of fixed lease payments over the lease term. To the extent a lease agreement includes an extension option that is reasonably certain to be exercised, we have recognized those amounts as part of our right-of-use assets and lease liabilities. Leases with an initial term of 12 months or less with purchase options or extension options that are not reasonably certain to be exercised are not recorded on the balance sheet; we recognize lease expense for these leases on a straight-line basis over the term of the lease. We combine lease and non-lease components, such as common area maintenance costs, in calculating the right-of-use assets and lease liabilities for all asset groups except for our CPAs, which contain embedded leases for regional aircraft. In addition to the lease component cost for regional aircraft, our CPAs also include non-lease components primarily related to the regional carriers' operating costs incurred in providing regional aircraft services. We allocate consideration for the lease components and non-lease components of each CPA based on their relative standalone values.

Lease Cost. The Company's lease cost for the years ended December 31 included the following components (in millions):


	2023		2022		2021
Operating lease cost	$	925	$	941	$	958
Variable and short-term lease cost	3,028		2,603		2,291
Amortization of finance lease assets	52		72		89
Interest on finance lease liabilities	20		13		16
Sublease income	(39)		(33)		(26)
Total lease cost	$	3,986	$	3,596	$	3,328

Lease terms and commitments. United's leases include aircraft leases for aircraft that are directly leased by United and aircraft that are operated by regional carriers on United's behalf under CPAs (but excluding aircraft owned by United) and non-aircraft leases. Aircraft operating leases relate to leases of 70 mainline and 275 regional aircraft while finance leases relate to leases of 22 mainline and 13 regional aircraft. United's aircraft leases have remaining lease terms of 1 month to 12 years with expiration dates ranging from 2024 through 2035. Under the terms of most aircraft leases, United has the right to purchase the aircraft at the end of the lease term, in some cases at fair market value, and in others, at a percentage of cost.

In addition, United also has 42 leases of Boeing 737 MAX and Boeing 787 aircraft under various sale-leaseback transactions. These transactions did not qualify as a sale under Accounting Standards Codification Topic 606, Revenue from Contracts with Customers ("ASC Topic 606"), and, as such, the associated aircraft remain on the Company's consolidated balance sheet as part of Flight equipment. The related obligations are recorded in Current maturities of other financial liabilities and Other financial liabilities.

Non-aircraft leases have remaining lease terms of 1 month to 29 years.

The table below summarizes the Company's scheduled future minimum lease payments under operating and finance leases, recorded on the balance sheet, as of December 31, 2023 (in millions):


	Operating Leases		Finance Leases
2024	$	813	$	183
2025	726		60
2026	706		19
2027	885		9
2028	685		8
After 2028	2,942		5
Minimum lease payments	6,757		284
Imputed interest	(1,678)		(21)
Present value of minimum lease payments	5,079		263
Less: current maturities of lease obligations	(576)		(172)
Long-term lease obligations	$	4,503	$	91

As of December 31, 2023, we have additional leases of approximately $1.6 billion for several regional aircraft under CPAs, mainline aircraft, airport facility and office space leases, none of which had commenced as of such date. These leases will commence between 2024 and 2026 with lease terms of up to 12 years.


	Other Financial Liabilities
2024	$	178
2025	178
2026	178
2027	472
2028	147
After 2028	2,090
	3,243
Imputed interest	(921)
Current maturities of other financial liabilities	(57)
Other financial liabilities	$	2,265

Our lease agreements do not provide a readily determinable implicit rate nor is it available to us from our lessors. Instead, we estimate United's incremental borrowing rate based on information available at lease commencement in order to discount lease payments to present value. The table below presents additional information related to our leases as of December 31:


	2023		2022
Weighted-average remaining lease term - operating leases	10 years		10 years
Weighted-average remaining lease term - finance leases	2 years		3 years
Weighted-average remaining lease term - other financial liabilities	10 years		9 years
Weighted-average discount rate - operating leases	5.8	%	5.5	%
Weighted-average discount rate - finance leases	6.3	%	6.4	%
Weighted-average interest rate - other financial liabilities	5.3	%	6.0	%

The table below presents supplemental cash flow information related to leases during the year ended December 31 (in millions):


	2023		2022		2021
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows for operating leases	$	874	$	919	$	977
Operating cash flows for finance leases	21		13		18
Financing cash flows for finance leases	311		124		216

Regional CPAs. United has contractual relationships with various regional carriers to provide regional aircraft service branded as United Express. Under these CPAs, the Company pays the regional carriers contractually agreed fees (carrier costs) for operating these flights plus a variable rate adjustment based on agreed performance metrics, subject to annual adjustments. The fees are based on specific rates multiplied by specific operating statistics (e.g., block hours, departures), as well as fixed monthly amounts. Under these CPAs, the Company is also responsible for all fuel costs incurred, as well as landing fees and other costs, which are either passed through by the regional carrier to the Company without any markup or directly incurred by the Company. In some cases, the Company owns some or all of the aircraft subject to the CPA and leases such aircraft to the regional carrier. United's CPAs are for 413 regional aircraft as of December 31, 2023, and the CPAs have terms expiring through 2035. Aircraft operated under CPAs include aircraft leased directly from the regional carriers and those owned by United and operated by the regional carriers. See Part I, Item 2. Properties, of this report for additional information.

United recorded approximately $1.1 billion, $0.9 billion and $0.6 billion in expenses related to its CPAs with its regional carriers in which United is a minority shareholder, for the years ended December 31, 2023, 2022 and 2021, respectively. United had prepaid balances and notes receivables with combined carrying values of $84 million and $62 million with these companies, as of December 31, 2023 and 2022, respectively. There were $122 million and $118 million of liabilities due to these companies as of December 31, 2023 and 2022, respectively. The CPAs with these related parties were executed in the ordinary course of business.

In 2023, United amended several of its CPAs with certain of its regional carriers to increase the contractually agreed fees (carrier costs) paid to those carriers and to add additional aircraft that will replace existing aircraft near the end of their contractual terms. Separately, the Company terminated its CPA and related regional flight operations with Air Wisconsin in June 2023.

Our future commitments under our CPAs are dependent on numerous variables, and are, therefore, difficult to predict. The most important of these variables is the number of scheduled block hours. Although we are not required to purchase a minimum number of block hours under certain of our CPAs, we have set forth below estimates of our future payments under the CPAs based on our assumptions. The actual amounts we pay to our regional operators under CPAs could differ materially from these estimates. United's estimates of its future payments under all of the CPAs do not include the portion of the underlying obligation for any aircraft leased to a regional carrier or deemed to be leased from other regional carriers and facility rent that are disclosed as part of operating leases above. For purposes of calculating these estimates, we have assumed (1) the number of block hours flown is based on our anticipated level of flight activity or at any contractual minimum utilization levels if applicable, whichever is higher, (2) that we will reduce the fleet as rapidly as contractually allowed under each CPA, (3) that aircraft utilization, stage length and load factors will remain constant, (4) that each carrier's operational performance will remain at recent historic levels and (5) an annual projected inflation rate. These amounts exclude variable pass-through costs such as fuel and landing fees, among others. Based on these assumptions as of December 31, 2023, our estimated future payments through the end of the terms of our CPAs are presented in the table below (in billions):


2024	$	2.4
2025	2.1
2026	2.1
2027	1.6
2028	1.3
After 2028	4.1
	$	13.6

In January 2024, United amended several of its CPAs with certain of its regional carriers. These amendments will result in an increase to its future commitments under its CPAs by approximately $0.6 billion.

LEASES AND CAPACITY PURCHASE AGREEMENTS

Lease Cost. The Company's lease cost for the years ended December 31 included the following components (in millions):


	2023		2022		2021
Operating lease cost	$	925	$	941	$	958
Variable and short-term lease cost	3,028		2,603		2,291
Amortization of finance lease assets	52		72		89
Interest on finance lease liabilities	20		13		16
Sublease income	(39)		(33)		(26)
Total lease cost	$	3,986	$	3,596	$	3,328

Non-aircraft leases have remaining lease terms of 1 month to 29 years.

The table below summarizes the Company's scheduled future minimum lease payments under operating and finance leases, recorded on the balance sheet, as of December 31, 2023 (in millions):


	Operating Leases		Finance Leases
2024	$	813	$	183
2025	726		60
2026	706		19
2027	885		9
2028	685		8
After 2028	2,942		5
Minimum lease payments	6,757		284
Imputed interest	(1,678)		(21)
Present value of minimum lease payments	5,079		263
Less: current maturities of lease obligations	(576)		(172)
Long-term lease obligations	$	4,503	$	91


	Other Financial Liabilities
2024	$	178
2025	178
2026	178
2027	472
2028	147
After 2028	2,090
	3,243
Imputed interest	(921)
Current maturities of other financial liabilities	(57)
Other financial liabilities	$	2,265


	2023		2022
Weighted-average remaining lease term - operating leases	10 years		10 years
Weighted-average remaining lease term - finance leases	2 years		3 years
Weighted-average remaining lease term - other financial liabilities	10 years		9 years
Weighted-average discount rate - operating leases	5.8	%	5.5	%
Weighted-average discount rate - finance leases	6.3	%	6.4	%
Weighted-average interest rate - other financial liabilities	5.3	%	6.0	%

The table below presents supplemental cash flow information related to leases during the year ended December 31 (in millions):


	2023		2022		2021
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows for operating leases	$	874	$	919	$	977
Operating cash flows for finance leases	21		13		18
Financing cash flows for finance leases	311		124		216


2024	$	2.4
2025	2.1
2026	2.1
2027	1.6
2028	1.3
After 2028	4.1
	$	13.6

Consolidated Balance Sheets (UAH) (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Statement of Financial Position [Abstract]
Receivables, allowance for doubtful accounts	$ 18	$ 11
Aircraft fuel, spare parts and supplies, obsolescence allowance	689	610
Intangibles, accumulated amortization	1,495	1,472
Allowance for credit losses on notes receivable	$ 38	$ 21
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common shares, authorized (in shares)	1,000,000,000	1,000,000,000
Common shares, outstanding (in shares)	328,018,739	326,930,321

- Definition

Amount of allowance for credit loss on financing receivable. Excludes allowance for financing receivable covered under loss sharing agreement.

+ References + Details

Pension, Postretirement And Other Employee Benefit Plans - Allocation of Plan Assets (Details) - United Airlines, Inc.	12 Months Ended
	Dec. 31, 2023
Equity securities
Defined Benefit Plan Disclosure [Line Items]
Expected Long-Term Rate of Return	9.00%
Equity securities \| Minimum
Defined Benefit Plan Disclosure [Line Items]
Percent of Total	25.00%
Equity securities \| Maximum
Defined Benefit Plan Disclosure [Line Items]
Percent of Total	73.00%
Fixed-income securities
Defined Benefit Plan Disclosure [Line Items]
Expected Long-Term Rate of Return	8.00%
Fixed-income securities \| Minimum
Defined Benefit Plan Disclosure [Line Items]
Percent of Total	14.00%
Fixed-income securities \| Maximum
Defined Benefit Plan Disclosure [Line Items]
Percent of Total	53.00%
Alternatives
Defined Benefit Plan Disclosure [Line Items]
Expected Long-Term Rate of Return	8.00%
Alternatives \| Minimum
Defined Benefit Plan Disclosure [Line Items]
Percent of Total	3.00%
Alternatives \| Maximum
Defined Benefit Plan Disclosure [Line Items]
Percent of Total	27.00%

Statements of Consolidated Comprehensive Income (Loss) (UAH) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 2,618	$ 737	$ (1,964)
Other comprehensive income (loss), net of tax:
Employee benefit plans	(261)	1,145	199
Investments and other	24	(28)	(2)
Total other comprehensive income (loss), net of tax	(237)	1,117	197
Total comprehensive income (loss), net	$ 2,381	$ 1,854	$ (1,767)

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References

+ Details

- Definition

Amount after tax and reclassification adjustments of other comprehensive income (loss).

+ References

+ Details

Earnings (Loss) Per Share (Tables)

12 Months Ended

Dec. 31, 2023

Earnings Per Share [Abstract]

Computation of Earnings Per Share

The computations of UAL's basic and diluted earnings (loss) per share are set forth below for the years ended December 31 (in millions, except per share amounts):


	2023		2022		2021
Earnings (loss) available to common stockholders	$	2,618	$	737	$	(1,964)

Basic weighted-average shares outstanding	327.8		326.4		321.9
Dilutive effect of stock warrants (a)	2.2		1.5		—
Dilutive effect of employee stock awards	1.9		2.2		—
Diluted weighted-average shares outstanding	331.9		330.1		321.9

Earnings (loss) per share, basic	$	7.98	$	2.26	$	(6.10)
Earnings (loss) per share, diluted	$	7.89	$	2.23	$	(6.10)

Potentially dilutive securities (b)
Stock warrants (a)	1.5		3.5		0.9
Employee stock awards	0.6		0.7		0.7

(b) Weighted-average potentially dilutive securities outstanding excluded from the computation of diluted earnings per share because the securities would have had an antidilutive effect.

Income Taxes

12 Months Ended

Dec. 31, 2023

Income Tax Disclosure [Abstract]

INCOME TAXES

The income tax provision (benefit) differed from amounts computed at the statutory federal income tax rate and consisted of the following significant components (in millions):


	2023		2022		2021
Income tax provision (benefit) at statutory rate	$	711	$	208	$	(537)
State income tax provision (benefit), net of federal income tax benefit	46		13		(34)
Nondeductible employee meals	15		12		7
Nondeductible transportation fringe benefit	13		10		8
Valuation allowance	(21)		(10)		(38)
Other, net	5		20		1
Income tax expense (benefit)	$	769	$	253	$	(593)

Current	$	13	$	5	$	(10)
Deferred	756		248		(583)
Income tax expense (benefit)	$	769	$	253	$	(593)

Temporary differences and carryforwards that give rise to deferred tax assets and liabilities at December 31, 2023 and 2022 were as follows (in millions):


	UAL				United
	2023		2022		2023		2022
Deferred income tax asset (liability):
Federal and state net operating loss ("NOL") carryforwards	$	2,644	$	2,932	$	2,616	$	2,903
Deferred revenue	1,845		1,783		1,845		1,783
Employee benefits, including pension, postretirement and medical	695		606		695		606
Operating lease liabilities	1,134		1,118		1,134		1,118
Other financial liabilities	414		141		414		141
Interest expense carryforward	579		510		579		510
Other	575		576		575		576
Less: Valuation allowance	(179)		(199)		(179)		(199)
Total deferred tax assets	$	7,707	$	7,467	$	7,679	$	7,438

Depreciation	$	(6,782)	$	(5,844)	$	(6,782)	$	(5,844)
Operating lease right-of-use asset	(887)		(881)		(887)		(881)
Intangibles	(632)		(651)		(632)		(651)
Total deferred tax liabilities	$	(8,301)	$	(7,376)	$	(8,301)	$	(7,376)
Net deferred tax asset (liability)	$	(594)	$	91	$	(622)	$	62

United and its domestic consolidated subsidiaries file a consolidated federal income tax return with UAL. Under an intercompany tax allocation policy, United and its subsidiaries compute, record and pay UAL for their own tax liabilities as if they were separate companies filing separate returns. In determining their own tax liabilities, United and each of its subsidiaries take into account all tax credits or benefits generated and utilized as separate companies and they are each compensated for the aforementioned tax benefits on an annual basis.

The Company's federal and state NOL and tax credit carryforwards relate to current and prior years' NOLs and credits, which may be used to reduce tax liabilities in future years. These tax benefits are mostly attributable to federal pre-tax NOL carryforwards of $12.0 billion ($2.5 billion tax effected) for UAL. If not utilized these federal pre-tax NOLs will expire as follows (in billions): $0.2 in 2029 and $0.2 in 2033. The remaining $11.6 billion of NOLs has no expiration date. State pre-tax NOLs of $3.4 billion ($0.2 billion tax effected) expire over a 1 to 20-year period. Federal tax credits of $50 million will expire over a 1 to 20-year period and state tax credits of $56 million will expire over a 1 to 15-year period.

As of December 31, 2023, the Company has recorded $150 million of valuation allowance against its capital loss deferred tax assets. Capital losses have a limited carryforward period of five years, and they can be utilized only to the extent of capital gains. The Company does not anticipate generating sufficient capital gains to utilize the losses before they expire, therefore, a valuation allowance is necessary as of December 31, 2023. Additionally, the Company recorded a valuation allowance of $29 million on certain state deferred tax assets primarily due to state NOLs that have short expiration periods.

The Company's unrecognized tax benefits related to uncertain tax positions were $66 million, $58 million and $55 million at December 31, 2023, 2022 and 2021, respectively. All of the uncertain tax positions would affect the Company's effective tax rate if recognized. The changes in unrecognized tax benefits relating to settlements with taxing authorities, unrecognized tax benefits as a result of tax positions taken during a prior period and unrecognized tax benefits relating from a lapse of the statute of limitations were immaterial during 2023, 2022 and 2021. The Company does not expect significant increases or decreases in their unrecognized tax benefits within the next 12 months. There are no material amounts included in the balance at December 31, 2023 for tax positions for which the ultimate deductibility is highly certain but for which there is uncertainty about the timing of such deductibility.

The Company's federal income tax returns for tax years after 2002 remain subject to examination by the Internal Revenue Service (the "IRS") and state taxing jurisdictions.

- Definition

The entire disclosure for income taxes. Disclosures may include net deferred tax liability or asset recognized in an enterprise's statement of financial position, net change during the year in the total valuation allowance, approximate tax effect of each type of temporary difference and carryforward that gives rise to a significant portion of deferred tax liabilities and deferred tax assets, utilization of a tax carryback, and tax uncertainties information.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480990/946-20-50-13

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(h)(2))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480678/235-10-S99-1

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-Name Accounting Standards Codification
-Publisher FASB
-URI https://asc.fasb.org//740/tableOfContent

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 14
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482685/740-10-50-14

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 21
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482685/740-10-50-21

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 270
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482526/740-270-50-1

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 17
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482685/740-10-50-17

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SAB TOPIC 6.I.5.Q1)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479360/740-10-S99-1

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 2
-Subparagraph (SAB Topic 11.C)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479360/740-10-S99-2

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482603/740-30-50-2

+ Details

Pension, Postretirement And Other Employee Benefit Plans - Change in Assumption of Benefit Obligation (Details) $ in Millions	12 Months Ended
	Dec. 31, 2023 USD ($)
Pension Benefits
Schedule Of Defined Benefit Plans And Defined Contribution Plans Disclosures [Line Items]
100 basis points decrease in the weighted average discount rate	$ 858
100 basis points decrease in the weighted average discount rate	96
100 basis points decrease in the expected long-term rate of return on plan assets	35
Other Postretirement Benefits
Schedule Of Defined Benefit Plans And Defined Contribution Plans Disclosures [Line Items]
100 basis points decrease in the weighted average discount rate	48
100 basis points decrease in the weighted average discount rate	0
100 basis points decrease in the expected long-term rate of return on plan assets	$ 0

Statements of Consolidated Comprehensive Income (Loss) (UA) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Net income (loss)	$ 2,618	$ 737	$ (1,964)
Other comprehensive income (loss), net of tax:
Employee benefit plans	(261)	1,145	199
Investments and other	24	(28)	(2)
Total other comprehensive income (loss), net of tax	(237)	1,117	197
Total comprehensive income (loss), net	2,381	1,854	(1,767)
United Airlines, Inc.
Net income (loss)	2,620	739	(1,962)
Other comprehensive income (loss), net of tax:
Employee benefit plans	(261)	1,145	199
Investments and other	24	(28)	(2)
Total other comprehensive income (loss), net of tax	(237)	1,117	197
Total comprehensive income (loss), net	$ 2,383	$ 1,856	$ (1,765)

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References

+ Details

- Definition

Amount after tax and reclassification adjustments of other comprehensive income (loss).

+ References

+ Details

Leases and Capacity Purchase Agreements - Components of Lease Cost (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Leases [Abstract]
Operating lease cost	$ 925	$ 941	$ 958
Variable and short-term lease cost	3,028	2,603	2,291
Amortization of finance lease assets	52	72	89
Interest on finance lease liabilities	20	13	16
Sublease income	(39)	(33)	(26)
Total lease cost	$ 3,986	$ 3,596	$ 3,328

Pension, Postretirement And Other Employee Benefit Plans - Accumulated Benefit Obligation and Projected Benefit Obligation in Excess of Plan Assets (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Retirement Benefits [Abstract]
Projected benefit obligation	$ 4,407	$ 4,045
Accumulated benefit obligation	3,767	3,461
Fair value of plan assets	$ 3,435	$ 3,287

Share-Based Compensation Plans

12 Months Ended

Dec. 31, 2023

Share-Based Payment Arrangement [Abstract]

SHARE-BASED COMPENSATION PLANS

UAL maintains share-based compensation plans for our management employees and our non-employee directors. These plans provide for grants of nonqualified stock options; incentive stock options (within the meaning of Section 422 of the Internal Revenue Code of 1986); stock appreciation rights ("SARs"); restricted stock; RSUs; performance units; cash incentive awards and other equity-based and equity-related awards. An award (other than an option, SAR or cash incentive award) may provide the holder with dividends or dividend equivalents.

All awards are recorded as either equity or a liability in the Company's consolidated balance sheets. The share-based compensation expense is recorded in salaries and related costs.

During 2023, UAL granted share-based compensation awards pursuant to the United Airlines Holdings, Inc. 2021 Incentive Compensation Plan. These share-based compensation awards included approximately 2.6 million RSUs consisting of approximately 2.0 million time-vested RSUs and approximately 0.6 million performance-based RSUs. The time-vested RSUs vest pro-rata, a majority of which vest on February 28th of each year, over a three-year period from the date of grant. The performance-based RSUs vest upon continuous employment with the Company through December 31, 2025 and the achievement of certain financial, operational and diversity goals. RSUs are generally equity awards settled in stock for domestic employees and liability awards settled in cash for international employees. The cash payments are based on the 20-day average closing price of UAL common stock immediately prior to the vesting date.

The following table provides information related to UAL's share-based compensation plan cost for the years ended December 31 (in millions):


	2023		2022		2021
Compensation cost:
RSUs	$	78	$	87	$	236
Stock options	2		2		2
Total	$	80	$	89	$	238

The table below summarizes UAL's unearned compensation and weighted-average remaining period to recognize costs for all outstanding share-based awards that are probable of being achieved as of December 31, 2023 (in millions, except as noted):


	Unearned Compensation		Weighted-Average Remaining Period (in years)
RSUs	$	78	1.4
Stock options	3		2.7
Total	$	81

RSUs. The table below summarizes UAL's RSU activity for the years ended December 31 (shares in millions):


	Liability Awards	Equity Awards
	RSUs	RSUs	Weighted- Average Grant Price
Outstanding at December 31, 2020	0.4	3.2	$	53.41
Granted	0.4	2.9	52.18
Vested	(0.6)	(1.5)	51.35
Forfeited	—	(0.2)	46.77
Outstanding at December 31, 2021	0.2	4.4	53.63
Granted	0.1	2.3	31.96
Additional issuance due to achievement of performance metrics	—	1.6	58.17
Vested	(0.2)	(4.8)	56.00
Forfeited	—	(0.2)	53.03
Outstanding at December 31, 2022	0.1	3.3	37.88
Granted	0.1	2.5	43.42

Vested	(0.1)	(1.6)	44.03
Forfeited	—	(0.1)	36.90
Outstanding at December 31, 2023	0.1	4.1	38.86

The fair value of RSUs that vested in 2023, 2022 and 2021 was approximately $76 million, $274 million and $104 million, respectively.

As of December 31, 2023, UAL had recorded a liability of approximately $3 million related to its cash-settled RSUs. UAL paid approximately $3 million, $7 million and $29 million related to its cash-settled RSUs during 2023, 2022 and 2021, respectively.

Debt

12 Months Ended

Dec. 31, 2023

Debt Disclosure [Abstract]

DEBT


(In millions)	Maturity Dates			Interest Rate(s) at December 31, 2023						At December 31,
										2023		2022
Aircraft notes (a)	2024	—	2036	2.70	%	—		7.35	%	$	12,508	$	12,262
MileagePlus Senior Secured Notes		2027				6.50	%			2,660		3,420
MileagePlus Term Loan Facility (b)		2027				10.77	%			2,100		2,700
2026 and 2029 Notes	2026	—	2029	4.38	%	—		4.63	%	4,000		4,000
2021 Term Loans (b)		2028				9.22	%			3,870		4,913
Unsecured
Notes	2024	—	2025	4.88	%	—		5.00	%	596		596
PSP Notes (c)	2030	—	2031			1.00	%			3,181		3,181
Other unsecured debt	2024	—	2029	0.00	%	—		5.75	%	437		508
										29,352		31,580
Less: unamortized debt discount, premiums and debt issuance costs										(277)		(386)
Less: current portion of long-term debt										(4,018)		(2,911)
Long-term debt, net										$	25,057	$	28,283
(a)Financing includes variable rate debt based on the Secured Overnight Financing Rate ("SOFR") (or another index rate), generally subject to a floor, plus a specified margin of 0.49% to 2.25%. (b)Financing includes variable rate debt based on SOFR (or another index rate), subject to a floor, plus a specified margin of 3.75% to 5.25%. (c)The PSP Notes include $1.5 billion of indebtedness evidenced by a 10-year senior unsecured promissory note with Treasury provided under the PSP of the CARES Act ("PSP1"), $0.9 billion of indebtedness evidenced by a 10-year senior unsecured promissory note issued to Treasury pursuant to Payroll Support Program Extension Agreements under the CARES Act ("PSP2") and $0.8 billion of indebtedness evidenced by a 10-year senior unsecured promissory note issued to Treasury pursuant to the Payroll Support Program established under Section 7301 of the American Rescue Plan Act of 2021 ("PSP3"). These PSP Notes have a rate of 1.00% in years 1 through 5, and a rate of the SOFR plus 2.00% in years 6 through 10.

The table below presents the Company's contractual principal payments (not including debt discount or debt issuance costs) at December 31, 2023 under then-outstanding long-term debt agreements in each of the next five calendar years (in millions):


2024	$	4,018
2025	3,452
2026	5,245
2027	2,475
2028	5,306
After 2028	8,856
	$	29,352

Equipment Notes. On June 20, 2023, the Company and Wilmington Trust, National Association, as subordination agent and pass through trustee (the "Trustee") under a certain pass through trust newly formed by the Company, entered into the Note Purchase Agreement, dated as of June 20, 2023 (the "Note Purchase Agreement"). The Note Purchase Agreement provides for the issuance by the Company of equipment notes (the "Equipment Notes") in the aggregate principal amount of $1.3 billion to finance 39 Boeing aircraft delivered new to the Company from August 2022 to May 2023. Pursuant to the Note Purchase Agreement, the Trustee purchased Equipment Notes issued under a trust indenture and mortgage (each, an "Indenture" and, collectively, the "Indentures") with respect to each aircraft entered into by the Company and Wilmington Trust, National Association, as mortgagee. Each Indenture provides for the issuance of Equipment Notes in a single series, Series A, bearing interest at the rate of 5.80% per annum. The Equipment Notes were purchased by the Trustee, using the proceeds from the sale of Pass Through Certificates, Series 2023-1A, issued by a pass through trust newly-formed by the Company to facilitate the financing of the aircraft. The interest on the Equipment Notes is payable semi-annually on each January 15 and July 15, beginning on January 15, 2024. The principal payments on the Equipment Notes are scheduled on January 15 and July 15 of each year, beginning on July 15, 2024. The final payments on the Equipment Notes will be due on January 15, 2036. These Equipment Notes are reflected as part of Aircraft notes in the table above.

In addition to the Equipment Notes described above, United borrowed $0.4 billion aggregate principal amounts from various financial institutions to finance the purchase of aircraft. The notes evidencing these borrowings, which are secured by the related aircraft, mature in 2035 and have variable interest rates ranging from 7.31% to 7.35% at December 31, 2023.

In 2023, United prepaid $1.0 billion of the outstanding principal amount under the 2021 Term Loan Facility (as defined below). See Note 13 for information related to charges recorded as a result of this prepayment.

In 2021, United entered into a new Term Loan Credit and Guaranty Agreement (the "2021 Term Loan Facility") initially providing term loans (the "2021 Term Loans") up to an aggregate amount of $5.0 billion and a new Revolving Credit and Guaranty Agreement (the "2021 Revolving Credit Facility" and, together with the 2021 Term Loan Facility, the "2021 Loan Facilities") initially providing revolving loan commitments of up to $1.75 billion. As of December 31, 2023, we had $1.75 billion undrawn and available under our revolving credit facility. On February 15, 2024, the Company entered into an Amended and Restated Revolving Credit and Guaranty Agreement (the "Revolving Credit Facility") amending its 2021 Revolving Credit Facility increasing the borrowing capacity by $1.115 billion, which may be drawn upon until February 15, 2029, in the case of any Revolving Loans (as defined in the Revolving Credit Facility) made by the Extending Lenders (as defined in the Revolving Credit Facility), and April 21, 2025, in the case of any Revolving Loans made by the 2024 Non-Extending Lenders (as defined in the Revolving Credit Facility). The revolving loan commitments of the Extending Lenders equal $2.7 billion and the revolving loan commitments of the 2024 Non-Extending Lenders equal $165 million. The Revolving Loans, if any, will bear interest at a variable rate equal to Term SOFR (as defined in the Revolving Credit Facility), generally subject to a floor, plus a credit adjustment spread described in the Revolving Credit Facility, or, at United's election, another rate based on certain market interest rates, also generally subject to a floor, in each case plus a variable margin ranging from 3.00% to 3.50%, in the case of Term SOFR loans, and 2.00% to 2.50%, in the case of loans at other market rates.

On February 22, 2024, the Company also entered into Amendment No. 2 to Term Loan Credit and Guaranty Agreement (as amended, the "Term Loan Facility" and, together with the Revolving Credit Facility, the "Loan Facilities") and (i) used available cash in an amount equal to $1.37 billion to partially prepay the term loans under the 2021 Term Loans and (ii) borrowed the entire term loan commitment available under the Term Loan Facility in an amount equal to $2.5 billion and used the proceeds of such terms loans (the "Term Loans") to prepay in full the remaining outstanding principal balance under the Existing Term Loan Facility. The Term Loans will bear interest at a variable rate equal to Term SOFR (subject to a floor of 0.0%); or, at United's election, another rate based on certain market interest rates (subject to a floor of 1.0%), in each case plus a margin of 2.75%, in the case of Term SOFR loans, and 1.75%, in the case of loans at other market rates. The remaining balance of the Term Loans will be due and payable on its maturity date on February 22, 2031.

The Loan Facilities are secured on a senior basis by continuing security interests granted by United to the Collateral Trustee for the benefit of the lenders under the Loan Facilities, among other parties, on the following (the "Collateral"), subject to certain exclusions: (i) all of United's route authorities granted by the U.S. Department of Transportation to operate scheduled service between any international airport located in the United States and any international airport located in any country other than the United States (except Cuba), (ii) United's rights to substantially all of its landing and take-off slots at foreign and domestic airports, including at John F. Kennedy International Airport, LaGuardia Airport and Ronald Reagan Washington National Airport, and (iii) United's rights to use or occupy space at airport terminals, each to the extent necessary at the relevant time for servicing scheduled air carrier service authorized by an applicable route authority. The Collateral securing the Loan Facilities also presently secures on a senior basis the 2026 and 2029 Notes.

Our debt agreements contain customary terms and conditions as well as various affirmative, negative and financial covenants that, among other things, restrict the ability of the Company and its subsidiaries to incur additional indebtedness and pay dividends or repurchase stock. As of December 31, 2023, the Company was in compliance with its debt covenants. The collateral, covenants and cross default provisions of the Company's principal debt instruments that contain such provisions are summarized in the table below:


Debt Instrument			Collateral, Covenants and Cross Default Provisions
Aircraft notes and other notes payable			Secured by certain aircraft, spare engines and spare parts. The indentures contain events of default that are customary for aircraft financings, including in certain cases cross default to other related aircraft.
2021 Loan Facilities			Secured on a senior basis by security interests granted by the Company to the collateral trustee for the benefit of the lenders under the 2021 Loan Facilities, among other parties, on the following: (i) all of the Company's route authorities granted by the U.S. Department of Transportation to operate scheduled service between any international airport located in the United States and any international airport located in any country other than the United States (except Cuba), (ii) the Company's rights to substantially all of its landing and take-off slots at foreign and domestic airports, including at John F. Kennedy International Airport, LaGuardia Airport and Ronald Reagan Washington National Airport (subject to certain exclusions), and (iii) the Company's rights to use or occupy space at airport terminals, each to the extent necessary at the relevant time for servicing scheduled air carrier service authorized by an applicable route authority. The 2021 Loan Facilities contain negative covenants that, among other things, limit our ability under certain circumstances to create liens on the collateral, make certain dividends, conduct stock repurchases, make certain restricted investments and other restricted payments, and consolidate, merge, sell, or otherwise dispose of all or substantially all of our assets. The 2021 Loan Facilities also contain financial covenants that require the Company to maintain at least $2.0 billion of unrestricted liquidity at all times, which includes unrestricted cash, short-term investments and any undrawn amounts under any revolving credit facility, and to maintain a minimum ratio of appraised value of collateral to the outstanding debt secured by such collateral (including under the 2021 Loan Facilities) of 1.6 to 1.0, tested semi-annually. The 2021 Loan Facilities contain events of default customary for similar financings, including a cross-payment default and cross-acceleration to other material indebtedness.

2026 and 2029 Notes			The 2026 and 2029 Notes are secured on a senior basis by security interests granted by the Company to the collateral trustee for the benefit of the holders of the 2026 and 2029 Notes, among other parties, on the following: (i) all of the Company's route authorities granted by the U.S. Department of Transportation to operate scheduled service between any international airport located in the United States and any international airport located in any country other than the United States (except Cuba), (ii) the Company's rights to substantially all of its landing and take-off slots at foreign and domestic airports, including at John F. Kennedy International Airport, LaGuardia Airport and Ronald Reagan Washington National Airport (subject to certain exclusions), and (iii) the Company's rights to use or occupy space at airport terminals, each to the extent necessary at the relevant time for servicing scheduled air carrier service authorized by an applicable route authority. The indenture for these 2026 and 2029 Notes contains covenants that, among other things, limit our ability under certain circumstances to create liens on the collateral, make certain dividends, stock repurchases, restricted investments and other restricted payments, and consolidate, merge, sell, or otherwise dispose of all or substantially all of our assets. The indenture also contains a financial covenant that requires UAL to pay special interest in an additional amount equal to 2.0% per year of the principal amount of the 2026 and 2029 Notes for so long as it is unable to demonstrate that it maintains a minimum ratio of appraised value of collateral to the outstanding debt secured by such collateral (including the 2026 and 2029 Notes) of 1.6 to 1.0, tested semi-annually. The indenture contains events of default customary for similar financings, including a cross-payment default and cross-acceleration to other material indebtedness.
MileagePlus Senior Secured Notes and MileagePlus Term Loan Facility			Secured by first-priority security interests in substantially all of the assets of the Issuers, other than excluded property and subject to certain permitted liens, including security interests in specified cash accounts that include the accounts into which MileagePlus revenues are or will be paid by the Company's marketing partners and by the Company.
PSP Notes			The PSP Notes represent senior unsecured indebtedness of UAL. The PSP Notes are guaranteed by United. If any subsidiary of UAL (other than United) becomes, or is required to become, an obligor on unsecured indebtedness of UAL or any of its subsidiaries with a principal balance in excess of a specified amount, then such subsidiary shall be required to guarantee the obligations of the Company under the PSP Notes. Pursuant to the PSP Agreements, the Company and its affiliates will be required to comply with certain provisions including, among others, audit and reporting requirements and provisions restricting the payment of certain executive compensation until April 1, 2023.
Unsecured notes			The indentures for these notes contain covenants that, among other things, restrict the ability of the Company and its restricted subsidiaries (as defined in the indentures) to incur additional indebtedness and make certain dividends, stock repurchases, restricted investments and other restricted payments.

Significant Accounting Policies - Operating Revenue by Principal Geographic Region (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Disaggregation of Revenue [Line Items]
Total operating revenue	$ 53,717	$ 44,955	$ 24,634
Domestic (U.S. and Canada)
Disaggregation of Revenue [Line Items]
Total operating revenue	32,400	28,474	16,845
Atlantic
Disaggregation of Revenue [Line Items]
Total operating revenue	10,982	9,072	3,414
Pacific
Disaggregation of Revenue [Line Items]
Total operating revenue	5,267	2,927	1,507
Latin America
Disaggregation of Revenue [Line Items]
Total operating revenue	$ 5,068	$ 4,482	$ 2,868

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References + Details

- Definition

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 924
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 11.L)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479941/924-10-S99-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479806/606-10-50-5

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 30
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-30

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 42
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-42

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 22
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-22

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 32
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-32

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 40
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-40

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 22
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-22

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 32
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-32

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 41
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-41

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 4
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479806/606-10-50-4

+ Details

Pension, Postretirement And Other Employee Benefit Plans - Narrative (Details)	3 Months Ended	12 Months Ended
	Mar. 31, 2021 USD ($)	Dec. 31, 2023 USD ($) plan	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
Schedule Of Defined Benefit Plans And Defined Contribution Plans Disclosures [Line Items]
Number of defined benefit pension plans \| plan		2
Profit sharing and payroll tax expense		$ 681,000,000	$ 133,000,000	$ 0
IAM National Pension Plan
Schedule Of Defined Benefit Plans And Defined Contribution Plans Disclosures [Line Items]
Multi-employer plan contributions			533,000,000
United Airlines, Inc.
Schedule Of Defined Benefit Plans And Defined Contribution Plans Disclosures [Line Items]
Expense for defined contribution plans		$ 960,000,000	756,000,000	651,000,000
Minimum
Schedule Of Defined Benefit Plans And Defined Contribution Plans Disclosures [Line Items]
Percentage of pre-tax earnings paid for profit sharing plan		5.00%
Minimum \| United Airlines, Inc.
Schedule Of Defined Benefit Plans And Defined Contribution Plans Disclosures [Line Items]
Employer contribution percentage		1.00%
Maximum
Schedule Of Defined Benefit Plans And Defined Contribution Plans Disclosures [Line Items]
Percentage of pre-tax earnings paid for profit sharing plan		20.00%
Maximum \| United Airlines, Inc.
Schedule Of Defined Benefit Plans And Defined Contribution Plans Disclosures [Line Items]
Employer contribution percentage		16.00%
Other Postretirement Benefits
Schedule Of Defined Benefit Plans And Defined Contribution Plans Disclosures [Line Items]
Special termination benefits		$ 0	$ 0	(31,000,000)
Defined benefit plan, expected future employer contributions, next fiscal year		$ 104,000,000
Employee Separation \| Voluntary Separation Leave Programs
Schedule Of Defined Benefit Plans And Defined Contribution Plans Disclosures [Line Items]
Special termination benefits				31,000,000
Employee Separation \| Voluntary Separation Leave Programs \| Full-Time Employees
Schedule Of Defined Benefit Plans And Defined Contribution Plans Disclosures [Line Items]
Restructuring programs, one-time contribution per employee	$ 125,000			125,000
Employee Separation \| Voluntary Separation Leave Programs \| Part-Time Employees
Schedule Of Defined Benefit Plans And Defined Contribution Plans Disclosures [Line Items]
Restructuring programs, one-time contribution per employee	$ 75,000			$ 75,000

Significant Accounting Policies

12 Months Ended

Dec. 31, 2023

Accounting Policies [Abstract]

SIGNIFICANT ACCOUNTING POLICIES

(a)Use of Estimates—The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America ("GAAP") requires management to make estimates and assumptions that affect the amounts reported in these financial statements and accompanying notes. Actual results could differ from those estimates.

(b)Revenue Recognition—Passenger revenue is recognized when transportation is provided and Cargo revenue is recognized when shipments arrive at their destination. Other operating revenue is recognized as the related performance obligations are satisfied.

The Company's operating revenue by principal geographic region (as defined by the U.S. Department of Transportation) for the years ended December 31 is presented in the table below (in millions):


	2023		2022		2021
Domestic (U.S. and Canada)	$	32,400	$	28,474	$	16,845
Atlantic	10,982		9,072		3,414
Pacific	5,267		2,927		1,507
Latin America	5,068		4,482		2,868
Total	$	53,717	$	44,955	$	24,634

Ancillary Fees. The Company charges fees, separately from ticket sales, for certain ancillary services that are directly related to passengers' travel, such as baggage fees, premium seat fees, inflight amenity fees, and other ticket-related fees. These ancillary fees are part of the travel performance obligation and, as such, are recognized as passenger revenue when the travel occurs. The Company recorded $4.1 billion, $3.4 billion and $2.2 billion of ancillary fees within passenger revenue in the years ended December 31, 2023, 2022 and 2021, respectively.

(c)Ticket Taxes—Certain governmental taxes are imposed on the Company's ticket sales through a fee included in ticket prices. The Company collects these fees and remits them to the appropriate government agency. These fees are recorded on a net basis and, as a result, are excluded from revenue.

(d)Frequent Flyer Accounting—United's MileagePlus loyalty program builds customer loyalty by offering awards, benefits and services to program participants. Members in this program earn miles for travel on United, United Express, Star Alliance members and certain other airlines that participate in the program. Members can also earn miles by purchasing goods and services from our network of non-airline partners. We have contracts to sell miles to these partners with the terms extending from one to six years. These partners include domestic and international credit card issuers, retail merchants, hotels, car rental companies and our participating airline partners. Miles can be redeemed for free (other than taxes and government-imposed fees), discounted or upgraded air travel and non-travel awards.


	Year Ended December 31,
	2023		2022
Total Frequent flyer deferred revenue - beginning balance	$	6,675	$	6,282
Total miles awarded	3,297		2,558
Travel miles redeemed	(2,723)		(2,079)
Non-travel miles redeemed	(106)		(86)
Total Frequent flyer deferred revenue - ending balance	$	7,143	$	6,675

In the years ended December 31, 2023, 2022 and 2021, the Company recognized, in Other operating revenue, $2.7 billion, $2.4 billion and $1.8 billion, respectively, related to the marketing, advertising, non-travel miles redeemed (net of related costs) and other travel-related benefits of the mileage revenue associated with our various partner agreements including, but not limited to, our Co-Brand Agreement. The portion related to the MileagePlus miles awarded of the total amounts received from our various partner agreements is deferred and presented in the table above as an increase to Total Frequent flyer deferred revenue.

(e)Cash and Cash Equivalents and Restricted Cash—Highly liquid investments with a maturity of three months or less on their acquisition date are classified as cash and cash equivalents. Restricted cash is classified as short-term or long-term in the consolidated balance sheets based on the expected timing of return of the assets to the Company or payment to an outside party.


	At December 31,
	2023		2022		2021
Current assets:
Cash and cash equivalents	$	6,058	$	7,166	$	18,283
Restricted cash	31		45		37
Other assets:
Restricted cash	245		210		213
Total cash, cash equivalents and restricted cash shown in the statement of consolidated cash flows	$	6,334	$	7,421	$	18,533

(f)Investments—Highly liquid investments with maturities of greater than three months to a year, at the time of purchase, are classified as short-term investments and are stated at fair value. Investments with maturities beyond one year when purchased are classified as short-term investments if they are expected to be available to support our short-term liquidity needs. Our short-term investments in debt securities are classified as available-for-sale and are stated at fair value. Realized gains and losses on sales of these investments are reflected in Miscellaneous, net in the consolidated statements of operations. Unrealized gains and losses on available-for-sale debt securities are reflected as a component of accumulated other comprehensive income (loss). Equity investments are accounted for under the equity method if we are able to exercise significant influence over an investee. Equity investments for which we do not have significant influence are recorded at fair value or at cost, if fair value is not readily determinable, with adjustments for observable changes in price or impairments (referred to as the measurement alternative). Changes in fair value are recorded in Unrealized gains (losses) on investments, net in the consolidated statements of operations. See Note 8 of this report for additional information related to investments.

(g)Compensation received in connection with purchase agreements—The Company accounts for compensation received from vendors as deferred credits that will generally be recognized as a reduction to the cost of the asset received in future periods.

(h)Accounts Receivable—Accounts receivable primarily consist of amounts due from credit card companies, non-airline partners, and cargo customers. We provide an allowance for credit losses expected to be incurred. We base our allowance on various factors including, but not limited to, aging, payment history, write-offs, macro-economic indicators and other credit monitoring indicators. Credit loss expense and write-offs related to trade receivables were not material for the years ended December 31, 2023 and 2022.

(i)Aircraft Fuel, Spare Parts and Supplies—The Company accounts for aircraft fuel, spare parts and supplies at average cost and provides an obsolescence allowance for aircraft spare parts with an assumed residual value of 10% of original cost.

(j)Property and Equipment—The Company records additions to owned operating property and equipment at cost when acquired. Property under finance leases and the related obligation for future lease payments are recorded at an amount equal to the initial present value of those lease payments. Modifications that enhance the operating performance or extend the useful lives of airframes or engines are capitalized as property and equipment. We periodically receive credits in connection with the acquisition of aircraft and engines including those related to contractual damages related to delays in delivery. These credits are deferred until the aircraft and engines are delivered and then applied as a reduction to the cost of the related equipment.

Depreciation and amortization of owned depreciable assets is based on the straight-line method over the assets' estimated useful lives. Leasehold improvements are amortized over the remaining term of the lease, including estimated facility renewal options when renewal is reasonably certain at key airports, or the estimated useful life of the related asset, whichever is less. Properties under finance leases are amortized using the straight-line method over the life of the lease or, in the case of certain aircraft, over their estimated useful lives, whichever is shorter. Amortization of finance lease assets is included in depreciation and amortization expense. The estimated useful lives of property and equipment are as follows:


						Estimated Useful Life (in years)
Aircraft, spare engines and related rotable parts						25 to 30
Aircraft seats						10 to 15
Buildings						25 to 45
Other property and equipment						3 to 15
Computer software						5 to 15
Building improvements						1 to 40

As of December 31, 2023 and 2022, the Company had a carrying value of computer software of $453 million and $471 million, respectively. For the years ended December 31, 2023, 2022 and 2021, the Company's amortization expense related to computer software was $168 million, $166 million and $182 million, respectively. Aircraft, spare engines and related rotable parts were assumed to have residual values of approximately 10% of original cost, and other categories of property and equipment were assumed to have no residual value.

(k)Long-Lived Asset Impairments—The Company evaluates the carrying value of long-lived assets subject to amortization whenever events or changes in circumstances indicate that an impairment may exist. For purposes of this testing, the Company has generally identified the aircraft fleet type as the lowest level of identifiable cash flows for its mainline fleet and the contract level for its regional fleet under capacity purchase agreements ("CPAs"). An impairment charge is recognized when the asset's carrying value exceeds its net undiscounted future cash flows. The amount of the charge is the difference between the asset's carrying value and fair market value.

The Company recorded impairment charges related to certain of its aircraft of $97 million for the year ended December 31, 2021. See Note 13 of this report for additional information related to impairments.

(l)Intangibles—The Company has finite-lived and indefinite-lived intangible assets, including goodwill. Finite-lived intangible assets are amortized over their estimated useful lives. Goodwill and indefinite-lived intangible assets are not amortized but are reviewed for impairment on an annual basis as of October 1, or more frequently if events or circumstances indicate that the asset may be impaired. When there is a triggering event, the Company typically determines fair value using either market or a variation of the income approach valuation techniques. These

The following table presents information about the Company's goodwill and other intangible assets at December 31 (in millions):


	2023				2022
	Gross Carrying Amount		Accumulated Amortization		Gross Carrying Amount		Accumulated Amortization
Goodwill	$	4,527			$	4,527

Indefinite-lived intangible assets
China route authority	$	1,020			$	1,020
Airport slots	574				574
Tradenames and logos	593				593
Alliances	404				404
Total	$	2,591			$	2,591

Finite-lived intangible assets
Frequent flyer database	$	1,177	$	1,068	$	1,177	$	1,040
Hubs	145		131		145		124
Contracts	—		—		7		7
Other	307		296		314		301
Total	$	1,629	$	1,495	$	1,643	$	1,472

Amortization expense in 2023, 2022 and 2021 was $37 million, $41 million and $49 million, respectively. Projected amortization expense in 2024, 2025, 2026, 2027 and 2028 is $32 million, $28 million, $18 million, $11 million and $10 million, respectively.

(m)Labor Costs—The Company records expenses associated with new or amendable labor agreements when the amounts are probable and estimable. These could include costs associated with retro-active lump sum cash payments made in conjunction with the ratification of labor agreements. To the extent these upfront costs are in lieu of future pay increases, they would be capitalized and amortized over the term of the labor agreements. If not, these amounts would be expensed.

(n)Share-Based Compensation—The Company measures the cost of employee services received in exchange for an award of equity instruments based on the grant date fair value of the award. The resulting cost is recognized over the period during which an employee is required to provide service in exchange for the award, usually the vesting period. Obligations for cash-settled restricted stock units ("RSUs") are remeasured at fair value throughout the requisite service period at the close of the reporting period based upon UAL's stock price. In addition to the service requirement, certain RSUs have performance metrics that must be achieved prior to vesting. These awards are accrued based on the expected level of achievement at each reporting period. An adjustment is recorded each reporting period to adjust compensation expense based on the then current level of expected performance achievement for the performance-based awards. See Note 4 of this report for additional information on UAL's share-based compensation plans.

(o)Maintenance and Repairs—The cost of maintenance and repairs, including the cost of minor replacements, is charged to expense as incurred, except for costs incurred under our power-by-the-hour ("PBTH") engine maintenance agreements. PBTH contracts transfer certain risk to third-party service providers and fix the amount we pay per flight hour or per cycle to the service provider in exchange for maintenance and repairs under a predefined maintenance program. Under PBTH agreements, the Company recognizes expense at a level rate per engine hour, unless the level of service effort and the related payments during the period are substantially consistent, in which case the Company recognizes expense based on the amounts paid.

(p)Advertising—Advertising costs, which are included in Other operating expenses, are expensed as incurred. Advertising expenses were $221 million, $165 million and $99 million for the years ended December 31, 2023, 2022 and 2021, respectively.

(q)Third-Party Business—The Company has third-party business activity that includes ground handling, maintenance services, flight academy and frequent flyer award non-travel redemptions. Third-party business revenue is recorded in Other operating revenue. Expenses associated with these third-party business activities are recorded in Other operating expenses, except for non-travel mileage redemption. Non-travel mileage redemption expenses are recorded to Other operating revenue.

(r)Uncertain Income Tax Positions—The Company has recorded reserves for income taxes and associated interest that may become payable in future years. Although management believes that its positions taken on income tax matters are reasonable, the Company nevertheless established tax and interest reserves in recognition that various taxing authorities may challenge certain of the positions taken by the Company, potentially resulting in additional liabilities for taxes and interest. The Company's uncertain tax position reserves are reviewed periodically and are adjusted as events occur that affect its estimates, such as the availability of new information, the lapsing of applicable statutes of limitation, the conclusion of tax audits, the measurement of additional estimated liability, the identification of new tax matters, the release of administrative tax guidance affecting its estimates of tax liabilities, or the rendering of relevant court decisions. The Company records penalties and interest relating to uncertain tax positions as part of income tax expense in its consolidated statements of operations. See Note 6 of this report for additional information on UAL's uncertain tax positions.

(s)Recently Issued Accounting Standards— In June 2022, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") No. 2022-03, Fair Value Measurement (Topic 820): Fair Value Measurement of Equity Securities Subject to Contractual Sale Restrictions. Under this standard, a contractual restriction on the sale of an equity security is not considered in measuring the security's fair value. The standard also requires certain disclosures for equity securities that are subject to contractual sale restrictions. The ASU became effective January 1, 2024. We do not expect this ASU to have a material impact on the valuation of our equity investments; however, we may be required to include additional disclosures to the extent we have material equity investments subject to contractual sale restrictions.

Debt - Summary of Long-Term Debt (Details) - USD ($)	12 Months Ended
Debt - Summary of Long-Term Debt (Details) - USD ($)	Dec. 31, 2023	Dec. 31, 2022	Apr. 21, 2021
Debt Instrument [Line Items]
Long term debt	$ 29,352,000,000	$ 31,580,000,000
Less: unamortized debt discount, premiums and debt issuance costs	(277,000,000)	(386,000,000)
Less: current portion of long-term debt	(4,018,000,000)	(2,911,000,000)
Long-term debt, net	$ 25,057,000,000	28,283,000,000
Secured Debt \| Minimum
Debt Instrument [Line Items]
Fixed interest rate	7.31%
Secured Debt \| Maximum
Debt Instrument [Line Items]
Fixed interest rate	7.35%
Secured Debt \| Aircraft notes
Debt Instrument [Line Items]
Long term debt	$ 12,508,000,000	12,262,000,000
Secured Debt \| Aircraft notes \| Minimum
Debt Instrument [Line Items]
Fixed interest rate	2.70%
Secured Debt \| Aircraft notes \| Maximum
Debt Instrument [Line Items]
Fixed interest rate	7.35%
Secured Debt \| Aircraft notes \| SOFR \| Minimum
Debt Instrument [Line Items]
Basis spread on variable rate	0.49%
Secured Debt \| Aircraft notes \| SOFR \| Maximum
Debt Instrument [Line Items]
Basis spread on variable rate	2.25%
Secured Debt \| MileagePlus Senior Secured Notes
Debt Instrument [Line Items]
Fixed interest rate	6.50%
Long term debt	$ 2,660,000,000	3,420,000,000
Secured Debt \| MileagePlus Term Loan Facility
Debt Instrument [Line Items]
Fixed interest rate	10.77%
Long term debt	$ 2,100,000,000	$ 2,700,000,000
Secured Debt \| MileagePlus Term Loan Facility \| SOFR \| Maximum
Debt Instrument [Line Items]
Basis spread on variable rate	5.25%	5.25%
Secured Debt \| 2026 and 2029 Notes
Debt Instrument [Line Items]
Long term debt	$ 4,000,000,000	$ 4,000,000,000
Secured Debt \| 2026 and 2029 Notes \| Minimum
Debt Instrument [Line Items]
Fixed interest rate	4.38%
Secured Debt \| 2026 and 2029 Notes \| Maximum
Debt Instrument [Line Items]
Fixed interest rate	4.63%
Secured Debt \| 2021 Term Loans
Debt Instrument [Line Items]
Fixed interest rate	9.22%
Long term debt	$ 3,870,000,000	$ 4,913,000,000
Aggregate principal amount			$ 5,000,000,000
Secured Debt \| 2021 Term Loans \| SOFR \| Minimum
Debt Instrument [Line Items]
Basis spread on variable rate	3.75%	3.75%
Unsecured
Debt Instrument [Line Items]
Fixed interest rate		4.25%
Unsecured \| Notes
Debt Instrument [Line Items]
Long term debt	$ 596,000,000	$ 596,000,000
Unsecured \| Notes \| Minimum
Debt Instrument [Line Items]
Fixed interest rate	4.88%
Unsecured \| Notes \| Maximum
Debt Instrument [Line Items]
Fixed interest rate	5.00%
Unsecured \| Other unsecured debt
Debt Instrument [Line Items]
Long term debt	$ 437,000,000	508,000,000
Unsecured \| Other unsecured debt \| Minimum
Debt Instrument [Line Items]
Fixed interest rate	0.00%
Unsecured \| Other unsecured debt \| Maximum
Debt Instrument [Line Items]
Fixed interest rate	5.75%
Unsecured \| PSP Notes
Debt Instrument [Line Items]
Fixed interest rate	1.00%
Long term debt	$ 3,181,000,000	$ 3,181,000,000
Unsecured \| PSP Notes \| SOFR
Debt Instrument [Line Items]
Basis spread on variable rate	2.00%
Unsecured \| PSP1 Note
Debt Instrument [Line Items]
Term of debt	10 years
Aggregate principal amount	$ 1,500,000,000
Unsecured \| PSP2 Note
Debt Instrument [Line Items]
Term of debt	10 years
Aggregate principal amount	$ 900,000,000
Unsecured \| PSP3 Note
Debt Instrument [Line Items]
Term of debt	10 years
Aggregate principal amount	$ 800,000,000

Share-Based Compensation Plans - Summary of RSU and Restricted Stock Activity (Details) - $ / shares shares in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Liability Awards - RSUs
Awards
Outstanding (in shares)	0.1	0.2	0.4
Granted (in shares)	0.1	0.1	0.4
Additional issuance due to achievement of performance metrics		0.0
Vested (in shares)	(0.1)	(0.2)	(0.6)
Forfeited (in shares)	0.0	0.0	0.0
Outstanding (in shares)	0.1	0.1	0.2
Equity Awards - RSUs
Awards
Outstanding (in shares)	3.3	4.4	3.2
Granted (in shares)	2.5	2.3	2.9
Additional issuance due to achievement of performance metrics		1.6
Vested (in shares)	(1.6)	(4.8)	(1.5)
Forfeited (in shares)	(0.1)	(0.2)	(0.2)
Outstanding (in shares)	4.1	3.3	4.4
Weighted- Average Grant Price
Outstanding (in dollars per share)	$ 37.88	$ 53.63	$ 53.41
Granted (in dollars per share)	43.42	31.96	52.18
Additional issuance due to achievement of performance metrics (in dollars per share)		58.17
Vested (in dollars per share)	44.03	56.00	51.35
Forfeited (in dollars per share)	36.90	53.03	46.77
Outstanding (in dollars per share)	$ 38.86	$ 37.88	$ 53.63

Pension, Postretirement And Other Employee Benefit Plans - Pension and Other Postretirement Plan Assets (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Level 3
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	$ 322	$ 333	$ 435
Pension Benefits
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	3,599	3,467	4,626
Pension Benefits \| Level 1
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	87	64
Pension Benefits \| Level 2
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	501	569
Pension Benefits \| Level 3
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	276	285
Pension Benefits \| Assets Measured at NAV
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	2,735	2,549
Pension Benefits \| Equity securities funds
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	1,265	1,183
Pension Benefits \| Equity securities funds \| Level 1
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	74	58
Pension Benefits \| Equity securities funds \| Level 2
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	3	26
Pension Benefits \| Equity securities funds \| Level 3
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	134	114
Pension Benefits \| Equity securities funds \| Assets Measured at NAV
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	1,054	985
Pension Benefits \| Fixed-income securities
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	1,325	1,316
Pension Benefits \| Fixed-income securities \| Level 1
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	0	0
Pension Benefits \| Fixed-income securities \| Level 2
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	411	527
Pension Benefits \| Fixed-income securities \| Level 3
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	3	5
Pension Benefits \| Fixed-income securities \| Assets Measured at NAV
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	911	784
Pension Benefits \| Alternatives
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	779	887
Pension Benefits \| Alternatives \| Level 1
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	0	0
Pension Benefits \| Alternatives \| Level 2
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	0	0
Pension Benefits \| Alternatives \| Level 3
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	136	161
Pension Benefits \| Alternatives \| Assets Measured at NAV
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	643	726
Pension Benefits \| Other investments
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	230	81
Pension Benefits \| Other investments \| Level 1
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	13	6
Pension Benefits \| Other investments \| Level 2
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	87	16
Pension Benefits \| Other investments \| Level 3
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	3	5
Pension Benefits \| Other investments \| Assets Measured at NAV
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	127	54
Other Postretirement Benefits
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	46	48	$ 49
Other Postretirement Benefits \| Deposit administration fund
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	46	48
Other Postretirement Benefits \| Deposit administration fund \| Level 1
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	0	0
Other Postretirement Benefits \| Deposit administration fund \| Level 2
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	0	0
Other Postretirement Benefits \| Deposit administration fund \| Level 3
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	46	48
Other Postretirement Benefits \| Deposit administration fund \| Assets Measured at NAV
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	$ 0	$ 0

Debt - Narrative (Details)			12 Months Ended
Debt - Narrative (Details)	Feb. 22, 2024 USD ($)	Feb. 15, 2024 USD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Jun. 20, 2023 USD ($) aircraft	Apr. 21, 2021 USD ($)
Debt Instrument [Line Items]
Debt prepayment			$ 4,248,000,000	$ 4,011,000,000	$ 5,205,000,000
Secured Debt
Debt Instrument [Line Items]
Borrowing amount			400,000,000
Secured Debt \| Revolving Credit Facility
Debt Instrument [Line Items]
Available under revolving credit facility			$ 1,750,000,000
Secured Debt \| Revolving Credit Facility \| Subsequent Event
Debt Instrument [Line Items]
Change in borrowing capacity		$ 1,115,000,000
Secured Debt \| Revolving Credit Facility \| Subsequent Event \| Extending Lenders
Debt Instrument [Line Items]
Revolving loan commitment		2,700,000,000
Secured Debt \| Revolving Credit Facility \| Subsequent Event \| Non-Extending Lenders
Debt Instrument [Line Items]
Revolving loan commitment		$ 165,000,000
Secured Debt \| Minimum
Debt Instrument [Line Items]
Stated interest rate			7.31%
Secured Debt \| Minimum \| Revolving Credit Facility \| Subsequent Event \| Non-Extending Lenders \| Secured Overnight Financing Rate (SOFR)
Debt Instrument [Line Items]
Basis spread on variable rate		3.00%
Secured Debt \| Minimum \| Revolving Credit Facility \| Subsequent Event \| Non-Extending Lenders \| Other Market Rates
Debt Instrument [Line Items]
Basis spread on variable rate		2.00%
Secured Debt \| Maximum
Debt Instrument [Line Items]
Stated interest rate			7.35%
Secured Debt \| Maximum \| Revolving Credit Facility \| Subsequent Event \| Non-Extending Lenders \| Secured Overnight Financing Rate (SOFR)
Debt Instrument [Line Items]
Basis spread on variable rate		3.50%
Secured Debt \| Maximum \| Revolving Credit Facility \| Subsequent Event \| Non-Extending Lenders \| Other Market Rates
Debt Instrument [Line Items]
Basis spread on variable rate		2.50%
Secured Debt \| Borrowings Financing Aircraft Purchases
Debt Instrument [Line Items]
Aggregate principal amount						$ 1,300,000,000
Number of aircrafts financed \| aircraft						39
Stated interest rate						5.80%
Secured Debt \| Term Loan Facility
Debt Instrument [Line Items]
Prepayment of term loan facility			$ 1,000,000,000
Secured Debt \| Term Loan Facility \| Subsequent Event
Debt Instrument [Line Items]
Borrowing amount	$ 2,500,000,000
Secured Debt \| Term Loan Facility \| Subsequent Event \| Secured Overnight Financing Rate (SOFR)
Debt Instrument [Line Items]
Basis spread on variable rate	2.75%
Interest rate floor	0.00%
Secured Debt \| Term Loan Facility \| Subsequent Event \| Other Market Rates
Debt Instrument [Line Items]
Basis spread on variable rate	1.75%
Interest rate floor	1.00%
Secured Debt \| 2021 Term Loans
Debt Instrument [Line Items]
Aggregate principal amount							$ 5,000,000,000
Stated interest rate			9.22%
Secured Debt \| 2021 Term Loans \| Subsequent Event
Debt Instrument [Line Items]
Debt prepayment	$ 1,370,000,000

Share-Based Compensation Plans (Tables)

12 Months Ended

Dec. 31, 2023

Share-Based Payment Arrangement [Abstract]

The following table provides information related to UAL's share-based compensation plan cost for the years ended December 31 (in millions):


	2023		2022		2021
Compensation cost:
RSUs	$	78	$	87	$	236
Stock options	2		2		2
Total	$	80	$	89	$	238

Summary of Unearned Compensation and Weighted-Average Remaining Period to Recognize Costs


	Unearned Compensation		Weighted-Average Remaining Period (in years)
RSUs	$	78	1.4
Stock options	3		2.7
Total	$	81

Summary of RSU and Restricted Stock Activity

The table below summarizes UAL's RSU activity for the years ended December 31 (shares in millions):


	Liability Awards	Equity Awards
	RSUs	RSUs	Weighted- Average Grant Price
Outstanding at December 31, 2020	0.4	3.2	$	53.41
Granted	0.4	2.9	52.18
Vested	(0.6)	(1.5)	51.35
Forfeited	—	(0.2)	46.77
Outstanding at December 31, 2021	0.2	4.4	53.63
Granted	0.1	2.3	31.96
Additional issuance due to achievement of performance metrics	—	1.6	58.17
Vested	(0.2)	(4.8)	56.00
Forfeited	—	(0.2)	53.03
Outstanding at December 31, 2022	0.1	3.3	37.88
Granted	0.1	2.5	43.42

Vested	(0.1)	(1.6)	44.03
Forfeited	—	(0.1)	36.90
Outstanding at December 31, 2023	0.1	4.1	38.86

Share-Based Compensation Plans - Information Related to Share-Based Compensation Plan Cost (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation cost	$ 80	$ 89	$ 238
RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation cost	78	87	236
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation cost	$ 2	$ 2	$ 2

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

+ Details

Fair Value Measurements, Investments and Notes Receivable

12 Months Ended

Dec. 31, 2023

Fair Value Disclosures [Abstract]

FAIR VALUE MEASUREMENTS, INVESTMENTS AND NOTES RECEIVABLE

Fair Value Information. Accounting standards require us to use valuation techniques to measure fair value that maximize the use of observable inputs and minimize the use of unobservable inputs. These inputs are described in Note 7 of this report. The table below presents disclosures about the fair value of financial assets and liabilities measured at fair value on a recurring basis in the Company's financial statements as of December 31 (in millions):


	2023								2022
	Total		Level 1		Level 2		Level 3		Total		Level 1		Level 2		Level 3
Cash and cash equivalents	$	6,058	$	6,058	$	—	$	—	$	7,166	$	7,166	$	—	$	—
Restricted cash - current (Note 1)	31		31		—		—		45		45		—		—
Restricted cash - non-current (Note 1)	245		245		—		—		210		210		—		—
Short-term investments:
U.S. government and agency notes	8,257		—		8,257		—		8,914		—		8,914		—
Asset-backed securities	—		—		—		—		325		—		325		—
Certificates of deposit placed through an account registry service ("CDARS")	73		—		73		—		—		—		—		—
Corporate debt	—		—		—		—		9		—		9		—
Long-term investments:
Equity securities	177		177		—		—		189		189		—		—

Investments presented in the table above have the same fair value as their carrying value.

Short-term investments — The short-term investments shown in the table above are classified as available-for-sale and have remaining maturities of approximately 15 months or less.

Long-term investments: Equity securities — Represents equity and equity-linked securities (such as vested warrants) that make up United's investments in Azul Linhas Aéreas Brasileiras S.A., Archer Aviation Inc., Eve Holding, Inc., Mesa Air Group, Inc. ("Mesa") and Clear Secure, Inc.

Other fair value information - The table below presents the carrying values and estimated fair values of financial instruments not presented in the tables above as of December 31 (in millions). Carrying amounts include any related discounts, premiums and issuance costs:


	2023										2022
	Carrying Amount		Fair Value								Carrying Amount		Fair Value
			Total		Level 1		Level 2		Level 3				Total		Level 1		Level 2		Level 3
Long-term debt	$	29,075	$	28,302	$	—	$	22,543	$	5,759	$	31,194	$	29,371	$	—	$	23,990	$	5,381

Fair value of the financial instruments included in the tables above was determined as follows:


Description			Fair Value Methodology
Cash and cash equivalents and Restricted cash (current and non-current)			The carrying amounts of these assets approximate fair value.
Short-term and Long-term investments			Fair value is based on (a) the trading prices of the investment or similar instruments or (b) broker quotes obtained by third-party valuation services.
Long-term debt			Fair values were based on either market prices or the discounted amount of future cash flows using our current incremental rate of borrowing for similar liabilities or assets.

Equity Method Investments. As of December 31, 2023, United holds investments, accounted for using the equity method, with a combined carrying value of approximately $230 million. Significant equity method investments are described below:

•CommuteAir LLC. United owns a 40% minority ownership stake in CommuteAir LLC. CommuteAir currently operates 53 regional aircraft under a CPA that has a term through 2026.

•Republic Airways Holdings Inc. United holds a 19% minority interest in Republic Airways Holdings Inc., which is the parent company of Republic Airways Inc. ("Republic"). Republic currently operates 66 regional aircraft under CPAs that have terms through 2035.

•United Airlines Ventures Sustainable Flight Fund (the "Fund"). During the first quarter of 2023, United launched, through its corporate venture capital arm, United Airlines Ventures, the Fund, an investment vehicle designed to support start-ups focused on decarbonizing air travel by accelerating the research, production and technologies

associated with sustainable aviation fuel. As of December 31, 2023, the Company indirectly holds a 38% ownership interest in the Fund.

Other Investments. United has equity investments in Abra Group Limited, a multinational airline holding company, JetSuiteX, Inc., an independent air carrier doing business as JSX, as well as a number of companies with emerging technologies and sustainable solutions. None of these investments have readily determinable fair values. We account for these investments at cost less impairment, adjusted for observable price changes in orderly transactions for an identical or similar investment of the same issuer. As of December 31, 2023, the carrying value of these investments was $401 million.

Notes Receivable. As of December 31, 2023, the Company has $103 million of notes receivable, net of allowance for credit losses, the majority of which is from certain of its regional carriers. The current portions of the notes receivable are recorded in Receivables, less allowance for credit losses and the long-term portions are recorded in Investments in affiliates and other, less allowance for credit losses on the Company's consolidated balance sheet.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Commitments and Contingencies - Summary of Commitments Related to the Acquisition of Aircraft (Details) $ in Billions	Dec. 31, 2023 USD ($)
Commitments and Contingencies Disclosure [Abstract]
2024	$ 12.1
2025	7.9
2026	6.0
2027	4.5
2028	6.1
After 2028	23.5
Total	$ 60.1

Statements of Consolidated Operations (UAH) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Operating revenue:
Total operating revenue	$ 53,717	$ 44,955	$ 24,634
Operating expense:
Salaries and related costs	14,787	11,466	9,566
Aircraft fuel	12,651	13,113	5,755
Landing fees and other rent	3,076	2,576	2,416
Aircraft maintenance materials and outside repairs	2,736	2,153	1,316
Depreciation and amortization	2,671	2,456	2,485
Regional capacity purchase	2,400	2,299	2,147
Distribution expenses	1,977	1,535	677
Aircraft rent	197	252	228
Special charges	949	140	(3,367)
Other operating expenses	8,062	6,628	4,433
Total operating expense	49,506	42,618	25,656
Operating income (loss)	4,211	2,337	(1,022)
Nonoperating income (expense):
Interest expense	(1,956)	(1,778)	(1,657)
Interest income	827	298	36
Interest capitalized	182	105	80
Unrealized gains (losses) on investments, net	27	20	(34)
Miscellaneous, net	96	8	40
Total nonoperating expense, net	(824)	(1,347)	(1,535)
Income (loss) before income taxes	3,387	990	(2,557)
Income tax expense (benefit)	769	253	(593)
Net income (loss)	$ 2,618	$ 737	$ (1,964)
Earnings (loss) per share, basic (in dollars per share)	$ 7.98	$ 2.26	$ (6.10)
Earnings (loss) per share, diluted (in dollars per share)	$ 7.89	$ 2.23	$ (6.10)
Passenger revenue
Operating revenue:
Total operating revenue	$ 49,046	$ 40,032	$ 20,197
Cargo
Operating revenue:
Total operating revenue	1,495	2,171	2,349
Other operating revenue
Operating revenue:
Total operating revenue	$ 3,176	$ 2,752	$ 2,088

Cover Page - USD ($) $ in Billions	12 Months Ended
Cover Page - USD ($) $ in Billions	Dec. 31, 2023	Feb. 22, 2024	Jun. 30, 2023
Document Information [Line Items]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2023
Current Fiscal Year End Date	--12-31
Document Transition Report	false
Entity File Number	001-06033
Entity Registrant Name	United Airlines Holdings, Inc.
Entity Address, Address Line One	233 South Wacker Drive,
Entity Address, City or Town	Chicago,
Entity Address, State or Province	IL
Entity Address, Postal Zip Code	60606
City Area Code	(872)
Local Phone Number	825-4000
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	36-2675207
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	true
Document Financial Statement Error Correction [Flag]	false
Entity Shell Company	false
Entity Public Float			$ 17.9
Entity Common Stock, Shares Outstanding		328,025,881
Documents Incorporated by Reference	Certain information required by Items 10, 11, 12 and 13 of Part III of this Form 10-K is incorporated by reference for United Airlines Holdings, Inc. from its definitive proxy statement for its 2024 Annual Meeting of Stockholders.
Document Fiscal Period Focus	FY
Amendment Flag	false
Document Fiscal Year Focus	2023
Entity Central Index Key	0000100517
Common Stock
Document Information [Line Items]
Title of 12(b) Security	Common Stock, $0.01 par value
Trading Symbol	UAL
Security Exchange Name	NASDAQ
Preferred Stock Purchase Rights
Document Information [Line Items]
Title of 12(b) Security	Preferred Stock Purchase Rights
United Airlines, Inc.
Document Information [Line Items]
Entity File Number	001-10323
Entity Registrant Name	United Airlines, Inc.
Entity Address, Address Line One	233 South Wacker Drive,
Entity Address, City or Town	Chicago,
Entity Address, State or Province	IL
Entity Address, Postal Zip Code	60606
City Area Code	(872)
Local Phone Number	825-4000
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	74-2099724
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	false
Document Financial Statement Error Correction [Flag]	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		1,000
Entity Central Index Key	0000319687

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2023

Income Tax Disclosure [Abstract]

Income Tax Provision (Benefit) Differed from Amounts Computed at the Statutory Federal Income Tax Rate and Significant Components

The income tax provision (benefit) differed from amounts computed at the statutory federal income tax rate and consisted of the following significant components (in millions):


	2023		2022		2021
Income tax provision (benefit) at statutory rate	$	711	$	208	$	(537)
State income tax provision (benefit), net of federal income tax benefit	46		13		(34)
Nondeductible employee meals	15		12		7
Nondeductible transportation fringe benefit	13		10		8
Valuation allowance	(21)		(10)		(38)
Other, net	5		20		1
Income tax expense (benefit)	$	769	$	253	$	(593)

Current	$	13	$	5	$	(10)
Deferred	756		248		(583)
Income tax expense (benefit)	$	769	$	253	$	(593)

Temporary Differences and Carryforwards Giving Rise to Deferred Tax Assets and Liabilities

Temporary differences and carryforwards that give rise to deferred tax assets and liabilities at December 31, 2023 and 2022 were as follows (in millions):


	UAL				United
	2023		2022		2023		2022
Deferred income tax asset (liability):
Federal and state net operating loss ("NOL") carryforwards	$	2,644	$	2,932	$	2,616	$	2,903
Deferred revenue	1,845		1,783		1,845		1,783
Employee benefits, including pension, postretirement and medical	695		606		695		606
Operating lease liabilities	1,134		1,118		1,134		1,118
Other financial liabilities	414		141		414		141
Interest expense carryforward	579		510		579		510
Other	575		576		575		576
Less: Valuation allowance	(179)		(199)		(179)		(199)
Total deferred tax assets	$	7,707	$	7,467	$	7,679	$	7,438

Depreciation	$	(6,782)	$	(5,844)	$	(6,782)	$	(5,844)
Operating lease right-of-use asset	(887)		(881)		(887)		(881)
Intangibles	(632)		(651)		(632)		(651)
Total deferred tax liabilities	$	(8,301)	$	(7,376)	$	(8,301)	$	(7,376)
Net deferred tax asset (liability)	$	(594)	$	91	$	(622)	$	62

Leases and Capacity Purchase Agreements - Future Lease Payment under Terms of Capacity Purchase Agreement (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Lessee, Lease, Description [Line Items]
2024	$ 178
2025	178
2026	178
2027	472
2028	147
After 2028	2,090
Total	3,243
Imputed interest	(921)
Less: current maturities of lease obligations	(57)	$ (23)
Other financial liabilities	2,265	$ 844
Capacity Purchase Agreements
Lessee, Lease, Description [Line Items]
2024	2,400
2025	2,100
2026	2,100
2027	1,600
2028	1,300
After 2028	4,100
Total	$ 13,600

Statements of Consolidated Cash Flows (UA) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Operating Activities:
Net income (loss)	$ 2,618	$ 737	$ (1,964)
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities -
Deferred income tax (benefit)	756	248	(583)
Depreciation and amortization	2,671	2,456	2,485
Operating and non-operating special charges, non-cash portion	84	16	32
Unrealized (gains) losses on investments	(27)	(20)	34
Amortization of debt discount and debt issuance costs	139	156	171
Other operating activities	6	218	222
Changes in operating assets and liabilities -
Increase in receivables	(100)	(158)	(448)
Increase in prepaids and other assets	(463)	(86)	(292)
Increase (decrease) in advance ticket sales	(851)	1,200	1,521
Increase in frequent flyer deferred revenue	468	393	307
Increase in accounts payable	572	796	985
Increase (decrease) in other liabilities	1,038	110	(403)
Net cash provided by operating activities	6,911	6,066	2,067
Investing Activities:
Capital expenditures, net of flight equipment purchase deposit returns	(7,171)	(4,819)	(2,107)
Purchases of short-term and other investments	(9,470)	(11,232)	(68)
Proceeds from sale of short-term and other investments	10,519	2,084	397
Proceeds from sale of property and equipment	39	207	107
Other, net	(23)	(69)	(1)
Net cash used in investing activities	(6,106)	(13,829)	(1,672)
Financing Activities:
Proceeds from issuance of debt and other financial liabilities, net of discounts and fees	2,388	736	11,096
Payments of long-term debt, finance leases and other financial liabilities	(4,248)	(4,011)	(5,205)
Proceeds from issuance of parent company stock	0	0	532
Net cash provided by (used in) financing activities	(1,892)	(3,349)	6,396
Net increase (decrease) in cash, cash equivalents and restricted cash	(1,087)	(11,112)	6,791
Cash, cash equivalents and restricted cash at beginning of year	7,421	18,533	11,742
Cash, cash equivalents and restricted cash at end of year	6,334	7,421	18,533
Investing and Financing Activities Not Affecting Cash:
Property and equipment acquired through the issuance of debt, finance leases and other	777	19	814
Right-of-use assets acquired through operating leases	552	137	771
Lease modifications and lease conversions	546	(84)	123
Investment interests received in exchange for goods and services	33	103	295
Cash Paid During the Period for:
Interest	1,848	1,573	1,424
Income taxes	7	8	0
United Airlines, Inc.
Operating Activities:
Net income (loss)	2,620	739	(1,962)
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities -
Deferred income tax (benefit)	757	248	(583)
Depreciation and amortization	2,671	2,456	2,485
Operating and non-operating special charges, non-cash portion	84	16	32
Unrealized (gains) losses on investments	(27)	(20)	34
Amortization of debt discount and debt issuance costs	139	156	171
Other operating activities	7	218	222
Changes in operating assets and liabilities -
Increase in receivables	(100)	(158)	(448)
Increase in intercompany receivables	(33)	(76)	(28)
Increase in prepaids and other assets	(463)	(86)	(293)
Increase (decrease) in advance ticket sales	(851)	1,200	1,521
Increase in frequent flyer deferred revenue	468	393	307
Increase in accounts payable	572	796	985
Increase (decrease) in other liabilities	1,035	110	(403)
Net cash provided by operating activities	6,879	5,992	2,040
Investing Activities:
Capital expenditures, net of flight equipment purchase deposit returns	(7,171)	(4,819)	(2,107)
Purchases of short-term and other investments	(9,470)	(11,232)	(68)
Proceeds from sale of short-term and other investments	10,519	2,084	397
Proceeds from sale of property and equipment	39	207	107
Other, net	(23)	(69)	(1)
Net cash used in investing activities	(6,106)	(13,829)	(1,672)
Financing Activities:
Proceeds from issuance of debt and other financial liabilities, net of discounts and fees	2,388	736	11,096
Payments of long-term debt, finance leases and other financial liabilities	(4,248)	(4,011)	(5,205)
Proceeds from issuance of parent company stock	0	0	532
Net cash provided by (used in) financing activities	(1,860)	(3,275)	6,423
Net increase (decrease) in cash, cash equivalents and restricted cash	(1,087)	(11,112)	6,791
Cash, cash equivalents and restricted cash at beginning of year	7,421	18,533	11,742
Cash, cash equivalents and restricted cash at end of year	6,334	7,421	18,533
Investing and Financing Activities Not Affecting Cash:
Property and equipment acquired through the issuance of debt, finance leases and other	777	19	814
Right-of-use assets acquired through operating leases	552	137	771
Lease modifications and lease conversions	546	(84)	123
Investment interests received in exchange for goods and services	33	103	295
Cash Paid During the Period for:
Interest	1,848	1,573	1,424
Income taxes	$ 7	$ 8	$ 0

Earnings (Loss) Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Earnings Per Share [Abstract]
Earnings (loss) available to common stockholders	$ 2,618	$ 737	$ (1,964)
Basic weighted-average shares outstanding (in shares)	327.8	326.4	321.9
Dilutive effect of stock warrants (in shares)	2.2	1.5	0.0
Dilutive effect of employee stock awards (in shares)	1.9	2.2	0.0
Diluted weighted-average shares outstanding (in shares)	331.9	330.1	321.9
Earnings (loss) per share, basic (in dollars per share)	$ 7.98	$ 2.26	$ (6.10)
Earnings (loss) per share, diluted (in dollars per share)	$ 7.89	$ 2.23	$ (6.10)
Stock warrants
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive securities (in shares)	1.5	3.5	0.9
Employee stock awards
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive securities (in shares)	0.6	0.7	0.7

Special Charges (Credits)

12 Months Ended

Dec. 31, 2023

Restructuring and Related Activities [Abstract]

SPECIAL CHARGES (CREDITS)


Operating:	2023		2022		2021
Labor contract ratification bonuses	$	814	$	—	$	—
CARES Act grant	—		—		(4,021)
Severance and benefit costs	—		—		438
Impairment of assets	—		—		97
(Gains) losses on sale of assets and other special charges	135		140		119
Total operating special charges (credits)	949		140		(3,367)
Nonoperating unrealized (gains) losses on investments, net	(27)		(20)		34
Nonoperating debt extinguishment and modification fees	11		7		50
Nonoperating special termination benefits and settlement losses	—		—		31
Total nonoperating special charges and unrealized (gains) losses on investments, net	(16)		(13)		115
Total operating and nonoperating special charges (credits) and unrealized (gains) losses on investments, net	933		127		(3,252)
Income tax expense (benefit), net of valuation allowance	(214)		(33)		728
Total operating and nonoperating special charges (credits) and unrealized (gains) losses on investments, net of income taxes	$	719	$	94	$	(2,524)

2023

Labor contract ratification bonuses. During 2023, the Company recorded $814 million of expense associated with the agreements with ALPA, IAM and other work groups. See Note 12 for additional information.

(Gains) losses on sale of assets and other special charges. During 2023, the Company recorded $135 million of net charges primarily comprised of accelerated depreciation related to certain of the Company's assets that will be retired early, reserves for various legal matters, a write-down of flight training equipment that is being sold and other gains and losses on the sale of assets.

Nonoperating unrealized (gains) losses on investments, net. During 2023, the Company recorded gains of $27 million, primarily for the change in the market value of its investments in equity securities.

Nonoperating debt extinguishment and modification fees. During 2023, the Company recorded $11 million of charges primarily related to the prepayment of $1.0 billion of the outstanding principal amount under a 2021 term loan facility.

2022

(Gains) losses on sale of assets and other special charges. During 2022, the Company recorded $140 million of net charges primarily comprised of $94 million for various legal matters and $23 million related to certain contract disputes.

Nonoperating unrealized (gains) losses on investments, net. During 2022, the Company recorded gains of $20 million primarily related to the change in the market value of its investments in equity securities.

Nonoperating debt extinguishment and modification fees. During 2022, the Company recorded $7 million of charges primarily related to the early redemption of $400 million of the outstanding principal amount of its 4.25% senior notes due 2022.

2021

CARES Act grant. During 2021, the Company received approximately $5.8 billion in funding pursuant to the Payroll Support Program agreements under the CARES Act (the "PSP2 and PSP3 Agreements"), which included approximately $1.7 billion aggregate principal amount of unsecured promissory notes. The Company recorded $4.0 billion as grant income in Special charges (credits). The Company also recorded $99 million for the PSP2 Warrants and PSP3 Warrants issued to Treasury as part of the PSP2 and PSP3 Agreements, within stockholders' equity, as an offset to the grant income.

Severance and benefit costs. During 2021, the Company recorded $438 million of charges related to pay continuation and benefits-related costs provided to employees who chose to voluntarily separate from the Company. The Company offered, based on employee group, age and completed years of service, pay continuation, health care coverage, and travel privileges. Approximately 4,500 employees elected to voluntarily separate from the Company.

Impairment of assets. During 2021, the Company recorded the following impairment charges:

•$61 million, primarily comprised of impairment charges for 13 Airbus A319 aircraft and 13 Boeing 737-700 airframes as a result of the then-current market conditions for used aircraft, along with charges for cancelled induction projects related to these aircraft.

•$36 million of impairments related to 64 Embraer EMB 145LR aircraft and related spare engines that United retired from its regional fleet. The decision to retire these aircraft was triggered by the United Next aircraft order.

(Gains) losses on sale of assets and other special charges. During 2021, the Company recorded net charges of $119 million primarily related to a one-time bonus paid to employees for their continued efforts during the COVID-19 pandemic, incentives for its employees to receive a COVID-19 vaccination and the termination of the lease associated with three floors of its headquarters at the Willis Tower in Chicago, partially offset by gains primarily related to the sale of its former headquarters in suburban Chicago, aircraft sale-leaseback transactions and aircraft component manufacturer credits.

Nonoperating unrealized (gains) losses on investments, net. During 2021, the Company recorded losses of $34 million primarily for the change in the market value of its investments in equity securities.

Nonoperating debt extinguishment and modification fees. During 2021, the Company recorded $50 million of charges for fees and discounts related to the issuance of a new term loan and revolving credit facility and the prepayment of a CARES Act loan and a 2017 term loan and revolving credit facility.

Nonoperating special termination benefits and settlement losses. During 2021, as part of the first quarter voluntary leave programs, the Company recorded $31 million of special termination benefits in the form of additional subsidies for retiree medical costs for certain U.S.-based front-line employees. The subsidies were in the form of a one-time contribution to a notional retiree health account of $125,000 for full-time employees and $75,000 for part-time employees. See Note 7 of this report for additional information.

Leases and Capacity Purchase Agreements - Narrative (Details) $ in Millions	1 Months Ended	12 Months Ended
	Jan. 31, 2024 USD ($)	Dec. 31, 2023 USD ($) aircraft lease	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
Lessee, Lease, Description [Line Items]
Number of aircraft leases under various sale-leaseback transactions \| lease		42
Additional leases that have not yet commenced		$ 1,600
Lease terms of additional leases that have not yet commenced (up to)		12 years
Notes receivable		$ 103
Liabilities due		3,835	$ 3,395
Capacity Purchase Agreements \| Subsequent Event
Lessee, Lease, Description [Line Items]
Change in CPA future commitments	$ 600
United Airlines, Inc.
Lessee, Lease, Description [Line Items]
Liabilities due		$ 3,835	3,395
Cash Collateralized Letters of Credit \| United Airlines, Inc.
Lessee, Lease, Description [Line Items]
Number of regional aircraft \| aircraft		413
Mainline Aircraft
Lessee, Lease, Description [Line Items]
Number of aircraft subject to operating leases \| aircraft		70
Number of aircraft subject to finance leases \| aircraft		22
Mainline Aircraft \| Minimum
Lessee, Lease, Description [Line Items]
Initial term of operating leases		1 month
Mainline Aircraft \| Maximum
Lessee, Lease, Description [Line Items]
Initial term of operating leases		12 years
Regional Aircraft
Lessee, Lease, Description [Line Items]
Number of aircraft subject to operating leases \| aircraft		275
Number of aircraft subject to finance leases \| aircraft		13
Regional Aircraft \| United Airlines, Inc. \| Capacity Purchase Agreements
Lessee, Lease, Description [Line Items]
Expenses		$ 1,100	900	$ 600
Regional Aircraft \| United Airlines, Inc. \| Capacity Purchase Agreements \| Related Party
Lessee, Lease, Description [Line Items]
Notes receivable		84	62
Liabilities due		$ 122	$ 118
Non-Aircraft \| Minimum
Lessee, Lease, Description [Line Items]
Initial term of operating leases		1 month
Non-Aircraft \| Maximum
Lessee, Lease, Description [Line Items]
Initial term of operating leases		29 years

Statements of Consolidated Cash Flows (UAH) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Operating Activities:
Net income (loss)	$ 2,618	$ 737	$ (1,964)
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities -
Deferred income tax (benefit)	756	248	(583)
Depreciation and amortization	2,671	2,456	2,485
Operating and non-operating special charges, non-cash portion	84	16	32
Unrealized (gains) losses on investments	(27)	(20)	34
Amortization of debt discount and debt issuance costs	139	156	171
Other operating activities	6	218	222
Changes in operating assets and liabilities -
Increase in receivables	(100)	(158)	(448)
Increase in prepaids and other assets	(463)	(86)	(292)
Increase (decrease) in advance ticket sales	(851)	1,200	1,521
Increase in frequent flyer deferred revenue	468	393	307
Increase in accounts payable	572	796	985
Increase (decrease) in other liabilities	1,038	110	(403)
Net cash provided by operating activities	6,911	6,066	2,067
Investing Activities:
Capital expenditures, net of flight equipment purchase deposit returns	(7,171)	(4,819)	(2,107)
Purchases of short-term and other investments	(9,470)	(11,232)	(68)
Proceeds from sale of short-term and other investments	10,519	2,084	397
Proceeds from sale of property and equipment	39	207	107
Other, net	(23)	(69)	(1)
Net cash used in investing activities	(6,106)	(13,829)	(1,672)
Financing Activities:
Proceeds from issuance of debt and other financial liabilities, net of discounts and fees	2,388	736	11,096
Payments of long-term debt, finance leases and other financial liabilities	(4,248)	(4,011)	(5,205)
Proceeds from equity issuance	0	0	532
Other, net	(32)	(74)	(27)
Net cash provided by (used in) financing activities	(1,892)	(3,349)	6,396
Net increase (decrease) in cash, cash equivalents and restricted cash	(1,087)	(11,112)	6,791
Cash, cash equivalents and restricted cash at beginning of year	7,421	18,533	11,742
Cash, cash equivalents and restricted cash at end of year	6,334	7,421	18,533
Investing and Financing Activities Not Affecting Cash:
Property and equipment acquired through the issuance of debt, finance leases and other	777	19	814
Right-of-use assets acquired through operating leases	552	137	771
Lease modifications and lease conversions	546	(84)	123
Investment interests received in exchange for goods and services	33	103	295
Cash Paid During the Period for:
Interest	1,848	1,573	1,424
Income taxes	$ 7	$ 8	$ 0

Consolidated Balance Sheets (UA) (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Receivables, allowance for doubtful accounts	$ 18	$ 11
Aircraft fuel, spare parts and supplies, obsolescence allowance	689	610
Intangibles, accumulated amortization	1,495	1,472
Allowance for credit losses on notes receivable	$ 38	$ 21
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common shares, authorized (in shares)	1,000,000,000	1,000,000,000
Common shares, outstanding (in shares)	328,018,739	326,930,321
United Airlines, Inc.
Receivables, allowance for doubtful accounts	$ 18	$ 11
Aircraft fuel, spare parts and supplies, obsolescence allowance	689	610
Intangibles, accumulated amortization	1,495	1,472
Allowance for credit losses on notes receivable	$ 38	$ 21
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common shares, authorized (in shares)	1,000	1,000
Common shares, issued (in shares)	1,000	1,000
Common shares, outstanding (in shares)	1,000	1,000

- Definition

Amount of allowance for credit loss on financing receivable. Excludes allowance for financing receivable covered under loss sharing agreement.

+ References + Details

Commitments and Contingencies

12 Months Ended

Dec. 31, 2023

Commitments and Contingencies Disclosure [Abstract]

COMMITMENTS AND CONTINGENCIES

Commitments. As of December 31, 2023, United had firm commitments to purchase aircraft from The Boeing Company ("Boeing") and Airbus S.A.S. ("Airbus") presented in the table below:


		Contractual Aircraft Deliveries			Expected Aircraft Deliveries (b)
Aircraft Type	Number of Firm Commitments (a)	2024	2025	After 2025	2024	2025	After 2025
787	150	8	18	124	7	18	125
737 MAX 8	43	43	—	—	37	6	—
737 MAX 9	34	34	—	—	19	15	—
737 MAX 10	277	80	71	126	—	(c)	(c)
A321neo	126	26	38	62	25	24	77
A321XLR	50	—	8	42	—	1	49
A350	45	—	—	45	—	—	45
(a)United also has options and purchase rights for additional aircraft. (b)Expected aircraft deliveries reflect adjustments communicated by Boeing and Airbus or estimated by United. (c)Due to the delay in the certification of the 737 MAX 10 aircraft, we are unable to accurately forecast the expected delivery period.

The aircraft listed in the table above are scheduled for delivery through 2033. The amount and timing of the Company's future capital commitments could change to the extent that: (i) the Company and the aircraft manufacturers, with whom the Company has existing orders for new aircraft, agree to modify the contracts governing those orders; (ii) rights are exercised pursuant to the relevant agreements to cancel deliveries or modify the timing of deliveries; or (iii) the aircraft manufacturers are unable to deliver in accordance with the terms of those orders.


(in billions)
2024	$	12.1
2025	7.9
2026	6.0
2027	4.5
2028	6.1
After 2028	23.5
	$	60.1

Legal and Environmental. The Company has certain contingencies resulting from litigation and claims incident to the ordinary course of business. As of December 31, 2023, management believes, after considering a number of factors, including (but not limited to) the information currently available, the views of legal counsel, the nature of contingencies to which the Company is subject and prior experience, that its defenses and assertions in pending legal proceedings have merit and the ultimate disposition of any pending matter will not materially affect the Company's financial position, results of operations or cash flows. The Company records liabilities for legal and environmental claims when it is probable that a loss has been incurred and the amount is reasonably estimable. These amounts are recorded based on the Company's assessments of the likelihood of their eventual disposition.

During 2022, the Company recorded charges of $94 million as a result of a number of recent decisions that appear to impact the Company's ability to successfully assert, in certain cases, that federal law preempts state and local laws that conflict with union contracts and/or federal requirements.

Guarantees and Indemnifications. In the normal course of business, the Company enters into numerous real estate leasing and aircraft financing arrangements that have various guarantees included in the contracts. These guarantees are primarily in the form of indemnities under which the Company typically indemnifies the lessors and any tax/financing parties against liabilities that arise out of or relate to the use, operation or maintenance of the leased premises or financed aircraft. Currently, the Company believes that any future payments required under these guarantees or indemnities would be immaterial, as most liabilities and related indemnities are covered by insurance (subject to deductibles). Additionally, certain real estate leases

include indemnities for any environmental liability that may arise out of or relate to the use of the leased premises.

As of December 31, 2023, United is the guarantor of approximately $1.9 billion in aggregate principal amount of tax-exempt special facilities revenue bonds and interest thereon. These bonds, issued by various airport municipalities, are payable solely from rentals paid under long-term agreements with the respective governing bodies. The leasing arrangements associated with these obligations are accounted for as operating leases recognized on the Company's consolidated balance sheet with the associated expense recorded on a straight-line basis over the expected lease term. The obligations associated with these tax-exempt special facilities revenue bonds are included in our lease commitments disclosed in Note 10 of this report. All of these bonds are due between 2024 and 2041.

As of December 31, 2023, United is the guarantor of $77 million of aircraft mortgage debt issued by one of United's regional carriers. The aircraft mortgage debt is subject to similar increased cost provisions as described below for the Company's debt, and the Company would potentially be responsible for those costs under the guarantees.

As of December 31, 2023, United had $429 million of surety bonds securing various insurance related obligations with expiration dates through 2027.

Increased Cost Provisions. In United's financing transactions that include loans in which United is the borrower, United typically agrees to reimburse lenders for any reduced returns with respect to the loans due to any change in capital requirements and, in the case of loans with respect to which the interest rate is based on SOFR, for certain other increased costs that the lenders incur in carrying these loans as a result of any change in law, subject, in most cases, to obligations of the lenders to take certain limited steps to mitigate the requirement for, or the amount of, such increased costs. The Company elected to apply the guidance in Accounting Standards Codification 848, Reference Rate Reform, to contracts and transactions that transitioned from the London Interbank Offered Rate (LIBOR) to SOFR. The application of this guidance did not have any material impact on the Company's financial statements. At December 31, 2023, the Company had $11.3 billion of floating rate debt with remaining terms of up to approximately 12 years that are subject to these increased cost provisions. In several financing transactions involving loans or leases from non-U.S. entities, with remaining terms of up to approximately 12 years and an aggregate balance of $8.1 billion, the Company bears the risk of any change in tax laws that would subject loan or lease payments thereunder to non-U.S. entities to withholding taxes, subject to customary exclusions.

Fuel Consortia. United participates in numerous fuel consortia with other air carriers at major airports to reduce the costs of fuel distribution and storage. Interline agreements govern the rights and responsibilities of the consortia members and provide for the allocation of the overall costs to operate the consortia based on usage. The consortia (and in limited cases, the participating carriers) have entered into long-term agreements to lease certain airport fuel storage and distribution facilities that are typically financed through various debt obligations. In general, each consortium lease agreement requires the consortium to make lease payments in amounts sufficient to pay the maturing principal and interest payments on these debt obligations. As of December 31, 2023, approximately $2.5 billion principal amount of such loans was secured by significant fuel facility leases in which United participates, as to which United and each of the signatory airlines has provided indirect guarantees of the debt. As of December 31, 2023, the Company's contingent exposure was approximately $447 million principal amount of such obligations based on its recent consortia participation. The Company's contingent exposure could increase if the participation of other air carriers decreases. The guarantees will expire when these obligations are paid in full, which ranges from 2027 to 2056. The Company concluded it was not necessary to record a liability for these indirect guarantees.

Regional Capacity Purchase. As of December 31, 2023, United had 252 call options to purchase regional jet aircraft being operated by certain of its regional carriers with contract dates extending until 2037. These call options are exercisable upon wrongful termination or breach of contract, among other conditions.

Credit Card Processing Agreements. The Company has agreements with financial institutions that process customer credit card transactions for the sale of air travel and other services. Under certain of the Company's credit card processing agreements, the financial institutions in certain circumstances have the right to require that the Company maintain a reserve equal to a portion of advance ticket sales that has been processed by that financial institution, but for which the Company has not yet provided the air transportation. Such financial institutions may require additional cash or other collateral reserves to be established or additional withholding of payments related to receivables collected if the Company does not maintain certain minimum levels of unrestricted cash, cash equivalents and short-term investments (collectively, "Unrestricted Liquidity"). The Company's current level of Unrestricted Liquidity is substantially in excess of these minimum levels.

Labor Negotiations. As of December 31, 2023, United, including its subsidiaries, had approximately 103,300 employees. Approximately 83% of United's employees were represented by various U.S. labor organizations.

In January 2023, the Company's more than 8,000 technicians and related employees represented by the International Brotherhood of Teamsters ratified an extension to their labor contract with United. The agreement becomes amendable in

December 2024. On February 28, 2024, United and the IBT reached a tentative agreement for an extension to their labor contract. The agreement, if ratified, becomes amendable in December 2028. The tentative agreement provides competitive pay increases and improved several work rules.

In May 2023, nearly 30,000 fleet service, passenger service, storekeepers, maintenance instructors and fleet technical instructors and related employees represented by the International Association of Machinists & Aerospace Workers ("IAM") ratified five agreements with United. The ratified agreements are effective through 2025. The Company recorded a one-time $48 million expense in conjunction with the ratification. On February 23, 2024, United and the IAM ratified agreements covering the security guards in California and central load planners. The ratified agreements are effective through 2025.

In September 2023, the Company's pilots represented by ALPA ratified an agreement with United. The agreement includes numerous work rule changes and pay rate increases during the four-year term. The agreement also included a provision for a one-time $765 million payment upon ratification which was paid by December 31, 2023.

Pension, Postretirement And Other Employee Benefit Plans - Defined Benefit Plan Assets Measured at Fair Value Using Unobservable Inputs (Details) - Level 3 - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Defined Benefit Plan, Change in Fair Value of Plan Assets, Level 3 Reconciliation [Roll Forward]
Fair value of plan assets at beginning of year	$ 333	$ 435
Actual income (loss) on plan assets:
Sold during the year	(50)	34
Held at year end	55	(39)
Purchases, sales, issuances and settlements (net)	(16)	(97)
Fair value of plan assets at end of year	$ 322	$ 333

- Definition

Amount of asset segregated and restricted to provide benefit under defined benefit plan. Asset includes, but is not limited to, stock, bond, other investment, earning from investment, and contribution by employer and employee.

+ References + Details

Pension, Postretirement And Other Employee Benefit Plans - Reconciliation of the Change in Benefit Obligation and Plan Asset, Funded Status and Amounts Recognized in the Financial Statements (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligation	$ 3,910	$ 3,596
Change in projected benefit obligation:
Projected benefit obligation at beginning of year	4,181	6,473
Service cost	124	204	$ 239
Interest cost	217	188	184
Actuarial (gain) loss	204	(2,186)
Benefits paid	(177)	(464)
Other	1	(34)
Projected benefit obligation at end of year	4,550	4,181	6,473
Change in plan assets:
Fair value of plan assets at beginning of year	3,467	4,626
Actual income (loss) on plan assets	281	(678)
Employer contributions	22	8
Benefits paid	(177)	(464)
Other	6	(25)
Fair value of plan assets at end of year	3,599	3,467	4,626
Funded status—Net amount recognized	(951)	(714)
Amounts recognized in the consolidated balance sheets consist of:
Noncurrent asset	21	44
Current liability	(4)	(11)
Noncurrent liability	(968)	(747)
Total liability	(951)	(714)
Amounts recognized in accumulated other comprehensive income (loss) consist of:
Net actuarial loss	(242)	(77)
Prior service cost	0	(1)
Total accumulated other comprehensive loss	(242)	(78)
Other Postretirement Benefits
Change in projected benefit obligation:
Projected benefit obligation at beginning of year	788	1,129
Service cost	4	9	10
Interest cost	42	30	25
Plan participants' contributions	67	69
Actuarial (gain) loss	22	(270)
Benefits paid	(177)	(179)
Projected benefit obligation at end of year	746	788	1,129
Change in plan assets:
Fair value of plan assets at beginning of year	48	49
Actual income (loss) on plan assets	1	1
Employer contributions	107	108
Plan participants' contributions	67	69
Benefits paid	(177)	(179)
Fair value of plan assets at end of year	46	48	$ 49
Funded status—Net amount recognized	(700)	(740)
Amounts recognized in the consolidated balance sheets consist of:
Current liability	(63)	(69)
Noncurrent liability	(637)	(671)
Total liability	(700)	(740)
Amounts recognized in accumulated other comprehensive income (loss) consist of:
Net actuarial loss	309	369
Prior service cost	222	335
Total accumulated other comprehensive loss	$ 531	$ 704

Significant Accounting Policies - Roll Forward of Frequent Flier Deferred Revenue (Details) - Frequent Flyer - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Movement in Deferred Revenue [Roll Forward]
Total Frequent flyer deferred revenue - beginning balance	$ 6,675	$ 6,282
Total miles awarded	3,297	2,558
Travel miles redeemed	(2,723)	(2,079)
Non-travel miles redeemed	(106)	(86)
Total Frequent flyer deferred revenue - ending balance	$ 7,143	$ 6,675

Schedule II - Valuation and Qualifying Accounts

12 Months Ended

Dec. 31, 2023

SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract]

Schedule II - Valuation and Qualifying Accounts

Schedule II

Valuation and Qualifying Accounts

For the Years Ended December 31, 2023, 2022 and 2021


(In millions) Description	Balance at Beginning of Period		Additions Charged to Costs and Expenses		Deductions		Other		Balance at End of Period
Allowance for credit losses - receivables:
2023	$	11	$	27	$	23	$	3	$	18
2022	28		22		39		—		11
2021	78		3		53		—		28
Obsolescence allowance—spare parts:
2023	$	610	$	102	$	23	$	—	$	689
2022	546		73		9		—		610
2021	478		79		11		—		546
Allowance for credit losses - investments in affiliates and other:
2023	$	21	$	20	$	—	$	(3)	$	38
2022	622		20		539		(82)		21
2021	522		1		—		99		622
Valuation allowance for deferred tax assets:
2023	$	199	$	(21)	$	—	$	1	$	179
2022	210		(10)		—		(1)		199
2021	247		(38)		—		1		210

Accumulated Other Comprehensive Income (Loss)

12 Months Ended

Dec. 31, 2023

Equity [Abstract]

ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) ("AOCI")

The tables below present the components of the Company's AOCI, net of tax (in millions):


	Pension and Other Postretirement Liabilities			Investments and Other		Deferred Taxes (a)		Total
Balance at December 31, 2020	$	(1,102)		$	2	$	(39)	$	(1,139)
Change in value	239			(2)		(53)		184
Amounts reclassified to earnings	16		(b)	—		(3)		13
Balance at December 31, 2021	(847)			—		(95)		(942)
Change in value	1,474			(35)		(321)		1,118
Amounts reclassified to earnings	(1)		(b)	—		—		(1)
Balance at December 31, 2022	626			(35)		(416)		175
Change in value	(199)			31		38		(130)
Amounts reclassified to earnings	(138)		(b)	—		31		(107)
Balance at December 31, 2023	$	289		$	(4)	$	(347)	$	(62)

(a)Includes approximately $285 million of deferred income tax expense that will not be recognized in net income until the related pension and postretirement benefit obligations are fully extinguished. We consider all income sources, including other comprehensive income, in determining the amount of tax benefit allocated to results from operations. (b)This AOCI component is included in the computation of net periodic pension and other postretirement costs, specifically the following components: amortization of unrecognized (gain) loss, amortization of prior service credit and other. See Note 7 of this report for additional information on pensions and other postretirement liabilities.

Significant Accounting Policies - Reconciliation of Cash, Cash Equivalents and Restricted Cash (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 6,058	$ 7,166	$ 18,283
Restricted cash	31	45	37
Other assets:
Restricted cash	245	210	213
Total cash, cash equivalents and restricted cash shown in the statement of consolidated cash flows	$ 6,334	$ 7,421	$ 18,533	$ 11,742

Significant Accounting Policies - Information about Goodwill and Other Intangible Assets (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Accounting Policies [Abstract]
Goodwill	$ 4,527	$ 4,527
Indefinite-lived Intangible Assets [Line Items]
Gross Carrying Amount	2,591	2,591
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	1,629	1,643
Accumulated Amortization	1,495	1,472
China route authority
Indefinite-lived Intangible Assets [Line Items]
Gross Carrying Amount	1,020	1,020
Airport slots
Indefinite-lived Intangible Assets [Line Items]
Gross Carrying Amount	574	574
Tradenames and logos
Indefinite-lived Intangible Assets [Line Items]
Gross Carrying Amount	593	593
Alliances
Indefinite-lived Intangible Assets [Line Items]
Gross Carrying Amount	404	404
Frequent flyer database
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	1,177	1,177
Accumulated Amortization	1,068	1,040
Hubs
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	145	145
Accumulated Amortization	131	124
Contracts
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	0	7
Accumulated Amortization	0	7
Other
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	307	314
Accumulated Amortization	$ 296	$ 301

Pay vs Performance Disclosure - USD ($) $ in Millions	12 Months Ended
Pay vs Performance Disclosure - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Pay vs Performance Disclosure
Net income (loss)	$ 2,618	$ 737	$ (1,964)

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References

+ Details

Debt (Tables)

12 Months Ended

Dec. 31, 2023

Debt Disclosure [Abstract]

Summary of Long-Term Debt


(In millions)	Maturity Dates			Interest Rate(s) at December 31, 2023						At December 31,
										2023		2022
Aircraft notes (a)	2024	—	2036	2.70	%	—		7.35	%	$	12,508	$	12,262
MileagePlus Senior Secured Notes		2027				6.50	%			2,660		3,420
MileagePlus Term Loan Facility (b)		2027				10.77	%			2,100		2,700
2026 and 2029 Notes	2026	—	2029	4.38	%	—		4.63	%	4,000		4,000
2021 Term Loans (b)		2028				9.22	%			3,870		4,913
Unsecured
Notes	2024	—	2025	4.88	%	—		5.00	%	596		596
PSP Notes (c)	2030	—	2031			1.00	%			3,181		3,181
Other unsecured debt	2024	—	2029	0.00	%	—		5.75	%	437		508
										29,352		31,580
Less: unamortized debt discount, premiums and debt issuance costs										(277)		(386)
Less: current portion of long-term debt										(4,018)		(2,911)
Long-term debt, net										$	25,057	$	28,283
(a)Financing includes variable rate debt based on the Secured Overnight Financing Rate ("SOFR") (or another index rate), generally subject to a floor, plus a specified margin of 0.49% to 2.25%. (b)Financing includes variable rate debt based on SOFR (or another index rate), subject to a floor, plus a specified margin of 3.75% to 5.25%. (c)The PSP Notes include $1.5 billion of indebtedness evidenced by a 10-year senior unsecured promissory note with Treasury provided under the PSP of the CARES Act ("PSP1"), $0.9 billion of indebtedness evidenced by a 10-year senior unsecured promissory note issued to Treasury pursuant to Payroll Support Program Extension Agreements under the CARES Act ("PSP2") and $0.8 billion of indebtedness evidenced by a 10-year senior unsecured promissory note issued to Treasury pursuant to the Payroll Support Program established under Section 7301 of the American Rescue Plan Act of 2021 ("PSP3"). These PSP Notes have a rate of 1.00% in years 1 through 5, and a rate of the SOFR plus 2.00% in years 6 through 10.

Contractual Principal Payments under Outstanding Long-Term Debt Agreements


2024	$	4,018
2025	3,452
2026	5,245
2027	2,475
2028	5,306
After 2028	8,856
	$	29,352

Summary of Collateral Covenants and Cross Default Provisions

The collateral, covenants and cross default provisions of the Company's principal debt instruments that contain such provisions are summarized in the table below:


Debt Instrument			Collateral, Covenants and Cross Default Provisions
Aircraft notes and other notes payable			Secured by certain aircraft, spare engines and spare parts. The indentures contain events of default that are customary for aircraft financings, including in certain cases cross default to other related aircraft.
2021 Loan Facilities			Secured on a senior basis by security interests granted by the Company to the collateral trustee for the benefit of the lenders under the 2021 Loan Facilities, among other parties, on the following: (i) all of the Company's route authorities granted by the U.S. Department of Transportation to operate scheduled service between any international airport located in the United States and any international airport located in any country other than the United States (except Cuba), (ii) the Company's rights to substantially all of its landing and take-off slots at foreign and domestic airports, including at John F. Kennedy International Airport, LaGuardia Airport and Ronald Reagan Washington National Airport (subject to certain exclusions), and (iii) the Company's rights to use or occupy space at airport terminals, each to the extent necessary at the relevant time for servicing scheduled air carrier service authorized by an applicable route authority. The 2021 Loan Facilities contain negative covenants that, among other things, limit our ability under certain circumstances to create liens on the collateral, make certain dividends, conduct stock repurchases, make certain restricted investments and other restricted payments, and consolidate, merge, sell, or otherwise dispose of all or substantially all of our assets. The 2021 Loan Facilities also contain financial covenants that require the Company to maintain at least $2.0 billion of unrestricted liquidity at all times, which includes unrestricted cash, short-term investments and any undrawn amounts under any revolving credit facility, and to maintain a minimum ratio of appraised value of collateral to the outstanding debt secured by such collateral (including under the 2021 Loan Facilities) of 1.6 to 1.0, tested semi-annually. The 2021 Loan Facilities contain events of default customary for similar financings, including a cross-payment default and cross-acceleration to other material indebtedness.

2026 and 2029 Notes			The 2026 and 2029 Notes are secured on a senior basis by security interests granted by the Company to the collateral trustee for the benefit of the holders of the 2026 and 2029 Notes, among other parties, on the following: (i) all of the Company's route authorities granted by the U.S. Department of Transportation to operate scheduled service between any international airport located in the United States and any international airport located in any country other than the United States (except Cuba), (ii) the Company's rights to substantially all of its landing and take-off slots at foreign and domestic airports, including at John F. Kennedy International Airport, LaGuardia Airport and Ronald Reagan Washington National Airport (subject to certain exclusions), and (iii) the Company's rights to use or occupy space at airport terminals, each to the extent necessary at the relevant time for servicing scheduled air carrier service authorized by an applicable route authority. The indenture for these 2026 and 2029 Notes contains covenants that, among other things, limit our ability under certain circumstances to create liens on the collateral, make certain dividends, stock repurchases, restricted investments and other restricted payments, and consolidate, merge, sell, or otherwise dispose of all or substantially all of our assets. The indenture also contains a financial covenant that requires UAL to pay special interest in an additional amount equal to 2.0% per year of the principal amount of the 2026 and 2029 Notes for so long as it is unable to demonstrate that it maintains a minimum ratio of appraised value of collateral to the outstanding debt secured by such collateral (including the 2026 and 2029 Notes) of 1.6 to 1.0, tested semi-annually. The indenture contains events of default customary for similar financings, including a cross-payment default and cross-acceleration to other material indebtedness.
MileagePlus Senior Secured Notes and MileagePlus Term Loan Facility			Secured by first-priority security interests in substantially all of the assets of the Issuers, other than excluded property and subject to certain permitted liens, including security interests in specified cash accounts that include the accounts into which MileagePlus revenues are or will be paid by the Company's marketing partners and by the Company.
PSP Notes			The PSP Notes represent senior unsecured indebtedness of UAL. The PSP Notes are guaranteed by United. If any subsidiary of UAL (other than United) becomes, or is required to become, an obligor on unsecured indebtedness of UAL or any of its subsidiaries with a principal balance in excess of a specified amount, then such subsidiary shall be required to guarantee the obligations of the Company under the PSP Notes. Pursuant to the PSP Agreements, the Company and its affiliates will be required to comply with certain provisions including, among others, audit and reporting requirements and provisions restricting the payment of certain executive compensation until April 1, 2023.
Unsecured notes			The indentures for these notes contain covenants that, among other things, restrict the ability of the Company and its restricted subsidiaries (as defined in the indentures) to incur additional indebtedness and make certain dividends, stock repurchases, restricted investments and other restricted payments.

- Definition

Tabular disclosure of long-debt instruments or arrangements, including identification, terms, features, collateral requirements and other information necessary to a fair presentation. These are debt arrangements that originally required repayment more than twelve months after issuance or greater than the normal operating cycle of the entity, if longer.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 69B
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481568/470-20-55-69B

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 69E
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481568/470-20-55-69E

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 3
-Subparagraph (SX 210.12-04(a))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480678/235-10-S99-3

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482925/835-30-45-2

Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 1A
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482925/835-30-45-1A

Reference 6: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-3

Reference 7: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480566/210-10-S99-1

Reference 8: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482949/835-30-55-8

Reference 9: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 50
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480848/942-470-50-3

Reference 10: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 8
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-8

Reference 11: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-6

Reference 12: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 7
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-7

+ Details

Insider Trading Arrangements	3 Months Ended
Insider Trading Arrangements	Dec. 31, 2023
Trading Arrangements, by Individual
Rule 10b5-1 Arrangement Adopted	false
Non-Rule 10b5-1 Arrangement Adopted	false
Rule 10b5-1 Arrangement Terminated	false
Non-Rule 10b5-1 Arrangement Terminated	false

Significant Accounting Policies - Estimated Useful Lives of Property and Equipment (Details)	Dec. 31, 2023
Aircraft, spare engines and related rotable parts \| Minimum
Property, Plant and Equipment [Line Items]
Estimated useful life	25 years
Aircraft, spare engines and related rotable parts \| Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life	30 years
Aircraft seats \| Minimum
Property, Plant and Equipment [Line Items]
Estimated useful life	10 years
Aircraft seats \| Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life	15 years
Buildings \| Minimum
Property, Plant and Equipment [Line Items]
Estimated useful life	25 years
Buildings \| Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life	45 years
Other property and equipment \| Minimum
Property, Plant and Equipment [Line Items]
Estimated useful life	3 years
Other property and equipment \| Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life	15 years
Computer software \| Minimum
Property, Plant and Equipment [Line Items]
Estimated useful life	5 years
Computer software \| Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life	15 years
Building improvements \| Minimum
Property, Plant and Equipment [Line Items]
Estimated useful life	1 year
Building improvements \| Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life	40 years

Fair Value Measurements, Investments and Notes Receivable (Tables)

12 Months Ended

Dec. 31, 2023

Fair Value Disclosures [Abstract]

Financial Assets and Liabilities Measured at Fair Value on Recurring Basis

The table below presents disclosures about the fair value of financial assets and liabilities measured at fair value on a recurring basis in the Company's financial statements as of December 31 (in millions):


	2023								2022
	Total		Level 1		Level 2		Level 3		Total		Level 1		Level 2		Level 3
Cash and cash equivalents	$	6,058	$	6,058	$	—	$	—	$	7,166	$	7,166	$	—	$	—
Restricted cash - current (Note 1)	31		31		—		—		45		45		—		—
Restricted cash - non-current (Note 1)	245		245		—		—		210		210		—		—
Short-term investments:
U.S. government and agency notes	8,257		—		8,257		—		8,914		—		8,914		—
Asset-backed securities	—		—		—		—		325		—		325		—
Certificates of deposit placed through an account registry service ("CDARS")	73		—		73		—		—		—		—		—
Corporate debt	—		—		—		—		9		—		9		—
Long-term investments:
Equity securities	177		177		—		—		189		189		—		—

Carrying Values and Estimated Fair Values of Financial Instruments

The table below presents the carrying values and estimated fair values of financial instruments not presented in the tables above as of December 31 (in millions). Carrying amounts include any related discounts, premiums and issuance costs:


	2023										2022
	Carrying Amount		Fair Value								Carrying Amount		Fair Value
			Total		Level 1		Level 2		Level 3				Total		Level 1		Level 2		Level 3
Long-term debt	$	29,075	$	28,302	$	—	$	22,543	$	5,759	$	31,194	$	29,371	$	—	$	23,990	$	5,381

Description of Fair Value of Financial Instruments and Fair Value Methodology

Fair value of the financial instruments included in the tables above was determined as follows:


Description			Fair Value Methodology
Cash and cash equivalents and Restricted cash (current and non-current)			The carrying amounts of these assets approximate fair value.
Short-term and Long-term investments			Fair value is based on (a) the trading prices of the investment or similar instruments or (b) broker quotes obtained by third-party valuation services.
Long-term debt			Fair values were based on either market prices or the discounted amount of future cash flows using our current incremental rate of borrowing for similar liabilities or assets.

Pension, Postretirement And Other Employee Benefit Plans - Components of Net Periodic Benefit Cost (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Pension Benefits
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost		$ 124	$ 204	$ 239
Interest cost		217	188	184
Expected return on plan assets		(251)	(306)	(283)
Amortization of unrecognized actuarial (gain) loss		8	120	170
Amortization of prior service credits		1	0	0
Special termination benefits - Voluntary Programs		0	0	0
Curtailment		0	0	(8)
Other		3	5	5
Net periodic benefit cost (credit)		102	211	307
Pension Benefits \| Forecast
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Net periodic benefit cost (credit)	$ 108
Other Postretirement Benefits
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost		4	9	10
Interest cost		42	30	25
Expected return on plan assets		(1)	(1)	(1)
Amortization of unrecognized actuarial (gain) loss		(38)	(14)	(28)
Amortization of prior service credits		(112)	(112)	(123)
Special termination benefits - Voluntary Programs		0	0	31
Curtailment		0	0	0
Other		0	0	0
Net periodic benefit cost (credit)		$ (105)	$ (88)	$ (86)
Other Postretirement Benefits \| Forecast
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Net periodic benefit cost (credit)	$ (78)

Fair Value Measurements, Investments and Notes Receivable - Narrative (Details) $ in Millions	12 Months Ended
	Dec. 31, 2023 USD ($) aircraft
Fair Value [Line Items]
Investments in securities accounted for under the equity method	$ 230
Carrying amount of loan receivable	$ 103
Maximum \| Corporate Debt
Fair Value [Line Items]
Available for sale investment maturity term	15 months
Champlain
Fair Value [Line Items]
Number of regional aircraft \| aircraft	53
Republic
Fair Value [Line Items]
Number of regional aircraft \| aircraft	66
Champlain
Fair Value [Line Items]
Ownership stake	40.00%
Republic
Fair Value [Line Items]
Ownership stake	19.00%
UAV Fund
Fair Value [Line Items]
Ownership stake	38.00%
Fulcrum BioEnergy, Inc., Boom, Alder Fuels LLC, Heart Aerospace Incorporated and ZeroAvia, Inc.
Fair Value [Line Items]
Carrying value of other investment	$ 401