View Filing Data

$ 41,303

$ 37,784

^[1]

$ 36,558

^[1]

Salaries and related costs

11,458

10,941

^[1]

10,176

^[1]

9,307

6,913

^[1]

5,813

^[1]

2,601

2,232

^[1]

2,197

^[1]

2,359

2,240

^[1]

2,165

^[1]

Aircraft maintenance materials and outside repairs

2,240

2,149

^[1],[2]

1,977

^[1],[2]

1,767

1,856

^[1]

1,749

^[1]

Distribution expenses

1,558

1,435

^[1]

1,395

^[1]

Aircraft rent

433

621

^[1]

680

^[1]

Special charges

487

176

^[1]

745

^[1]

Other operating expenses

5,801

5,550

^[1]

5,317

^[1]

Total operating expense

38,011

34,113

^[1]

32,214

^[1]

3,292

3,671

^[1]

4,344

^[1]

(729)

(671)

^[1]

(674)

^[1]

^[1]

Interest income

101

^[1]

(76)

(101)

^[1]

(11)

^[1]

(634)

(631)

^[1]

(571)

^[1]

2,658

3,040

^[1]

3,773

^[1]

529

896

^[1]

1,539

^[1]

$ 2,129

$ 2,144

^{[1],[2],[3],[4]}

$ 2,234

^{[1],[2],[3],[4]}

$ 7.73

$ 7.08

^[1]

$ 6.77

^[1]

$ 7.70

$ 7.06

^[1]

$ 6.76

^[1]

$ 41,303

$ 37,784

^[5]

$ 36,558

^[5]

Salaries and related costs

11,458

10,941

^[5]

10,176

^[5]

9,307

6,913

^[5]

5,813

^[5]

2,601

2,232

^[5]

2,197

^[5]

2,359

2,240

^[5]

2,165

^[5]

Aircraft maintenance materials and outside repairs

2,240

2,149

^[5],[6]

1,977

^[5],[6]

1,767

1,856

^[5]

1,749

^[5]

Distribution expenses

1,558

1,435

^[5]

1,395

^[5]

Aircraft rent

433

621

^[5]

680

^[5]

Special charges

487

176

^[5]

745

^[5]

Other operating expenses

5,799

5,548

^[5]

5,315

^[5]

Total operating expense

38,009

34,111

^[5]

32,212

^[5]

3,294

3,673

^[5]

4,346

^[5]

(729)

(671)

^[5]

(674)

^[5]

^[5]

Interest income

101

^[5]

(76)

(101)

^[5]

(11)

^[5]

(634)

(631)

^[5]

(571)

^[5]

2,660

3,042

^[5]

3,775

^[5]

529

879

^[5]

1,541

^[5]

2,131

2,163

^[6],[7],[8]

2,234

^[6],[7],[8]

Passenger revenue

Passenger revenue | United Airlines, Inc.

37,706

34,460

^[1]

33,429

^[1]

37,706

34,460

^[5]

33,429

^[5]

Cargo

Cargo | United Airlines, Inc.

1,237

1,114

^[1]

934

^[1]

1,237

1,114

^[5]

934

^[5]

Other operating revenue

Other operating revenue | United Airlines, Inc.

2,360

2,210

^[1]

2,195

^[1]

$ 2,360

$ 2,210

^[5]

$ 2,195

^[5]

[1]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606) and Accounting Standards Update No. 2017-07, Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost. See Note 1 to the financial statements contained in Part II, Item 8 of this report for additional information.
[2]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606). See Note 1 to the financial statements contained in Part II, Item 8 of this report for additional information.
[3]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606). See Note 1 to the financial statements contained in Part II, Item 8 of this report for additional information.
[4]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606). See Note 1 to the financial statements contained in Part II, Item 8 of this report for additional information.
[5]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606) and Accounting Standards Update No. 2017-07, Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost. See Note 1 to the financial statements contained in Part II, Item 8 of this report for additional information.
[6]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606). See Note 1 to the financial statements contained in Part II, Item 8 of this report for additional information.
[7]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606). See Note 1 to the financial statements contained in Part II, Item 8 of this report for additional information.
[8]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606). See Note 1 to the financial statements contained in Part II, Item 8 of this report for additional information.

Statements of Consolidated Comprehensive Income (Loss) - USD ($)
$ in Millions

12 Months Ended

Dec. 31, 2018

Dec. 31, 2017

Dec. 31, 2016

Other comprehensive income (loss), net change related to:

$ 2,129

$ 2,144

^{[1],[2],[3],[4]}

$ 2,234

^{[1],[2],[3],[4]}

Employee benefit plans, net of taxes

342

(195)

(313)

Fuel derivative financial instruments, net of taxes

316

Investments and other, net of taxes

(4)

(6)

(1)

Total other comprehensive income (loss), net

338

(200)

Total comprehensive income, net

2,467

1,944

2,236

Other comprehensive income (loss), net change related to:

2,131

2,163

^[5],[6],[7]

2,234

^[5],[6],[7]

Employee benefit plans, net of taxes

342

(195)

^[5]

(313)

^[5]

Fuel derivative financial instruments, net of taxes

^[5]

316

^[5]

Investments and other, net of taxes

(4)

(6)

^[5]

(1)

^[5]

Total other comprehensive income (loss), net

338

(200)

^[5]

Total comprehensive income, net

$ 2,469

$ 1,963

^[5]

$ 2,236

^[5]

[1]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606) and Accounting Standards Update No. 2017-07, Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost. See Note 1 to the financial statements contained in Part II, Item 8 of this report for additional information.
[2]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606). See Note 1 to the financial statements contained in Part II, Item 8 of this report for additional information.
[3]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606). See Note 1 to the financial statements contained in Part II, Item 8 of this report for additional information.
[4]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606). See Note 1 to the financial statements contained in Part II, Item 8 of this report for additional information.
[5]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606). See Note 1 to the financial statements contained in Part II, Item 8 of this report for additional information.
[6]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606). See Note 1 to the financial statements contained in Part II, Item 8 of this report for additional information.
[7]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606). See Note 1 to the financial statements contained in Part II, Item 8 of this report for additional information.

Consolidated Balance Sheets - USD ($)
$ in Millions

Dec. 31, 2018

Dec. 31, 2017

Receivables, less allowance for doubtful accounts (2018—$8; 2017—$7)

$ 1,694

$ 1,482

^[1]

Short-term investments

2,256

2,316

^[1]

1,346

1,340

^[1]

Aircraft fuel, spare parts and supplies, less obsolescence allowance (2018—$412; 2017—$354)

985

924

^[1]

913

1,071

^[1]

Total current assets

7,194

7,133

^[1]

Owned—

31,607

28,692

^[1]

Total owned property and equipment

7,919

6,946

^[1]

39,526

35,638

^[1]

Less—Accumulated depreciation and amortization

(12,760)

(11,159)

^[1]

Total owned property and equipment, net

26,766

24,479

^[1]

Purchase deposits for flight equipment

1,177

1,344

^[1]

Capital leases—

1,029

1,151

^[1]

Less—Accumulated amortization

^[1]

Total capital leases

1,040

1,162

^[1]

(654)

(777)

^[1]

Total capital leases, net

386

385

^[1]

Total operating property and equipment, net

28,329

26,208

^[1]

Intangibles, less accumulated amortization (2018—$1,380; 2017—$1,313)

Goodwill

4,523

^[1]

3,159

3,539

^[1]

Investments in affiliates and other, net

105

^[1]

Notes receivable, net

516

^[1]

966

806

^[1]

Total other assets

9,269

9,005

^[1]

Total assets

44,792

42,346

^[1]

4,381

3,940

^[1]

2,286

2,192

^[1]

Accrued salaries and benefits

2,363

2,196

^[1]

2,184

2,166

^[1]

Current maturities of long-term debt

1,230

1,565

^[1]

Current maturities of capital leases

149

128

^[1]

Total current liabilities

619

576

^[1]

13,212

12,763

^[1]

Long-term debt

12,215

11,703

^[1]

Long-term obligations under capital leases

1,134

996

^[1]

Postretirement benefit liability

2,719

2,591

^[1]

1,295

1,602

^[1]

Pension liability

1,576

1,921

^[1]

814

204

^[1]

Total other liabilities and deferred credits

1,832

^[1]

8,236

8,150

^[1]

Commitments and contingencies

Additional capital invested

Preferred stock

^[1]

Common stock

^[1]

6,120

6,098

^[1]

Stock held in treasury, at cost

6,668

4,549

^[1]

(1,993)

(769)

^[1]

Accumulated other comprehensive loss

(803)

(1,147)

^[1]

Total stockholders' equity

9,995

8,734

^[1]

Total liabilities and stockholders' equity

44,792

42,346

^[1]

Receivables, less allowance for doubtful accounts (2018—$8; 2017—$7)

1,688

1,476

^[2]

Short-term investments

2,256

2,316

^[2]

1,346

1,340

^[2]

Aircraft fuel, spare parts and supplies, less obsolescence allowance (2018—$412; 2017—$354)

985

924

^[2]

913

1,071

^[2]

Total current assets

7,188

7,127

^[2]

Owned—

31,607

28,692

^[2]

Total owned property and equipment

7,919

6,946

^[2]

39,526

35,638

^[2]

Less—Accumulated depreciation and amortization

(12,760)

(11,159)

^[2]

Total owned property and equipment, net

26,766

24,479

^[2]

Purchase deposits for flight equipment

1,177

1,344

^[2]

Capital leases—

1,029

1,151

^[2]

Less—Accumulated amortization

^[2]

Total capital leases

1,040

1,162

^[2]

(654)

(777)

^[2]

Total capital leases, net

386

385

^[2]

Total operating property and equipment, net

28,329

26,208

^[2]

Intangibles, less accumulated amortization (2018—$1,380; 2017—$1,313)

Goodwill

4,523

^[2]

3,159

3,539

^[2]

Investments in affiliates and other, net

105

^[2]

Notes receivable, net

516

^[2]

966

806

^[2]

Total other assets

9,269

9,005

^[2]

Total assets

44,786

42,340

^[2]

4,381

3,940

^[2]

2,286

2,192

^[2]

Accrued salaries and benefits

2,363

2,196

^[2]

2,184

2,166

^[2]

Current maturities of long-term debt

1,230

1,565

^[2]

Current maturities of capital leases

149

128

^[2]

Total current liabilities

624

581

^[2]

13,217

12,768

^[2]

Long-term debt

12,215

11,703

^[2]

Long-term obligations under capital leases

1,134

996

^[2]

Postretirement benefit liability

2,719

2,591

^[2]

1,295

1,602

^[2]

Pension liability

1,576

1,921

^[2]

842

231

^[2]

Total other liabilities and deferred credits

1,831

1,832

^[2]

8,263

8,177

^[2]

Commitments and contingencies

Additional capital invested

Common stock

^[2]

598

1,787

^[2]

Accumulated other comprehensive loss

10,272

8,146

^[2]

(803)

(1,147)

^[2]

Receivable from related parties

(110)

(90)

^[2]

Total stockholders' equity

9,957

8,696

^[2]

Total liabilities and stockholders' equity

$ 44,786

$ 42,340

^[2]

[1]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606). See Note 1 to the financial statements contained in Part II, Item 8 of this report for additional information.
[2]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606). See Note 1 to the financial statements contained in Part II, Item 8 of this report for additional information.

Consolidated Balance Sheets (Parenthetical) - USD ($)
$ in Millions

Dec. 31, 2018

Dec. 31, 2017

Receivables, allowance for doubtful accounts

$ 8

$ 7

^[1]

Aircraft fuel, spare parts and supplies, obsolescence allowance

412

354

^[1]

Intangibles, accumulated amortization

$ 1,380

$ 1,313

^[1]

Common stock, par value (in dollars per share)

$ 0.01

^[1]

Common shares, authorized (in shares)

1,000,000,000

^[1]

Common shares, outstanding (in shares)

269,914,769

286,973,195

^[1]

Receivables, allowance for doubtful accounts

$ 8

$ 7

^[2]

Aircraft fuel, spare parts and supplies, obsolescence allowance

412

354

^[2]

Intangibles, accumulated amortization

$ 1,380

$ 1,313

^[2]

Common stock, par value (in dollars per share)

$ 0.01

^[2]

Common shares, authorized (in shares)

1,000

^[2]

Common shares, issued (in shares)

1,000

^[2]

Common shares, outstanding (in shares)

1,000

^[2]

[1]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606). See Note 1 to the financial statements contained in Part II, Item 8 of this report for additional information.
[2]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606). See Note 1 to the financial statements contained in Part II, Item 8 of this report for additional information.

Statements of Consolidated Cash Flows - USD ($)
$ in Millions

12 Months Ended

Dec. 31, 2018

Dec. 31, 2017

Dec. 31, 2016

Operating Activities:

Adjustments to reconcile net income to net cash provided by operating activities -

$ 2,129

$ 2,144

^{[1],[2],[3],[4]}

$ 2,234

^{[1],[2],[3],[4]}

515

973

^[3]

1,631

^[3]

Special charges, non-cash portion

2,240

2,149

^[1],[3]

1,977

^[1],[3]

416

^[3]

391

^[3]

Other operating activities

170

141

^[3]

109

^[3]

Changes in operating assets and liabilities -

Increase in receivables

(29)

(183)

^[3]

(16)

^[3]

(Increase) decrease in other assets

(533)

^[3]

(296)

^[3]

Increase (decrease) in advance ticket sales

441

145

^[3]

(28)

^[3]

Increase (decrease) in frequent flyer deferred revenue

222

(107)

^[3]

(55)

^[3]

Increase in accounts payable

130

^[3]

239

^[3]

Decrease in advanced purchase of miles

(942)

^[3]

(206)

^[3]

Decrease in other liabilities

(82)

(475)

^[3]

(438)

^[3]

Net cash provided by operating activities

6,181

3,413

^[3]

5,542

^[3]

Investing Activities:

Capital expenditures

(4,177)

(3,998)

^[3]

(3,223)

^[3]

Purchases of short-term and other investments

(2,552)

(3,241)

^[3]

(2,768)

^[3]

Proceeds from sale of short-term and other investments

2,616

3,177

^[3]

2,712

^[3]

Loans made to others

(466)

(30)

^[3]

(56)

^[3]

Investment in affiliates

(139)

(2)

^[3]

(14)

^[3]

Net cash used in investing activities

155

164

^[3]

111

^[3]

(4,563)

(3,930)

^[3]

(3,238)

^[3]

Financing Activities:

Proceeds from issuance of long-term debt and airport construction financing

1,740

2,765

^[3]

808

^[3]

Payments of long-term debt

(1,727)

(901)

^[3]

(1,215)

^[3]

Principal payments under capital leases

(1,235)

(1,844)

^[3]

(2,614)

^[3]

(134)

(124)

^[3]

(136)

^[3]

Capitalized financing costs

(37)

(80)

^[3]

(64)

^[3]

Net cash used in financing activities

(17)

(11)

^[3]

(1,410)

(195)

^[3]

(3,213)

^[3]

Net increase (decrease) in cash, cash equivalents and restricted cash

208

(712)

^[3]

(909)

^[3]

Cash, cash equivalents and restricted cash at beginning of year

^[3]

1,591

2,303

3,212

Cash, cash equivalents and restricted cash at end of year

1,799

1,591

^[3]

2,303

^[3]

Investing and Financing Activities Not Affecting Cash:

Property and equipment acquired through the issuance of debt and capital leases

174

935

^[3]

386

^[3]

Debt associated with termination of a maintenance service agreement

163

^[3]

Investment in Republic Airways Holdings, Inc. received from bankruptcy claims

^[3]

Airport construction financing

^[3]

Operating lease conversions to capital lease

^[3]

Cash Paid During the Period for:

Interest

651

571

^[3]

584

^[3]

Income taxes

^[3]

Operating Activities:

Adjustments to reconcile net income to net cash provided by operating activities -

2,131

2,163

^[5],[6],[7]

2,234

^[5],[6],[7]

515

956

^[6]

1,633

^[6]

Special charges, non-cash portion

2,240

2,149

^[6],[8]

1,977

^[6],[8]

416

^[6]

391

^[6]

Other operating activities

170

140

^[6]

109

^[6]

Changes in operating assets and liabilities -

Increase in receivables

(29)

(183)

^[6]

(16)

^[6]

Increase in intercompany receivables

(20)

(15)

^[6]

(57)

^[6]

(Increase) decrease in other assets

(533)

^[6]

(250)

^[6]

Increase (decrease) in advance ticket sales

441

145

^[6]

(28)

^[6]

Increase (decrease) in frequent flyer deferred revenue

222

(107)

^[6]

(55)

^[6]

Increase in accounts payable

130

^[6]

239

^[6]

Decrease in advanced purchase of miles

(942)

^[6]

(206)

^[6]

Decrease in other liabilities

(82)

(475)

^[6]

(436)

^[6]

Net cash provided by operating activities

6,163

3,399

^[6]

5,535

^[6]

Investing Activities:

Capital expenditures

(4,177)

(3,998)

^[6]

(3,223)

^[6]

Proceeds from sale of short-term and other investments

(2,552)

(3,241)

^[6]

(2,768)

^[6]

Proceeds from sale of short-term and other investments

2,616

3,177

^[6]

2,712

^[6]

Loans made to others

(466)

(30)

^[6]

(56)

^[6]

Investment in affiliates

(139)

(2)

^[6]

(14)

^[6]

Net cash used in investing activities

155

164

^[6]

111

^[6]

(4,563)

(3,930)

^[6]

(3,238)

^[6]

Financing Activities:

Proceeds from issuance of long-term debt and airport construction financing

1,740

2,765

^[6]

808

^[6]

Payments of long-term debt

(1,727)

(901)

^[6]

(1,215)

^[6]

Principal payments under capital leases

(1,235)

(1,844)

^[6]

(2,614)

^[6]

(134)

(124)

^[6]

(136)

^[6]

Capitalized financing costs

(37)

(80)

^[6]

(64)

^[6]

Net cash used in financing activities

^[6]

(1,392)

(181)

^[6]

(3,206)

^[6]

Net increase (decrease) in cash, cash equivalents and restricted cash

208

(712)

^[6]

(909)

^[6]

Cash, cash equivalents and restricted cash at beginning of year

^[6]

1,585

2,297

3,206

Cash, cash equivalents and restricted cash at end of year

1,793

1,585

^[6]

2,297

^[6]

Investing and Financing Activities Not Affecting Cash:

Property and equipment acquired through the issuance of debt and capital leases

174

935

^[6]

386

^[6]

Debt associated with termination of a maintenance service agreement

163

^[6]

Investment in Republic Airways Holdings, Inc. received from bankruptcy claims

^[6]

Airport construction financing

^[6]

Operating lease conversions to capital lease

^[6]

Cash Paid During the Period for:

Interest

651

571

^[6]

584

^[6]

Income taxes

$ 19

$ 20

^[6]

$ 14

^[6]

[1]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606) and Accounting Standards Update No. 2017-07, Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost. See Note 1 to the financial statements contained in Part II, Item 8 of this report for additional information.
[2]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606). See Note 1 to the financial statements contained in Part II, Item 8 of this report for additional information.
[3]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606). See Note 1 to the financial statements contained in Part II, Item 8 of this report for additional information.
[4]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606). See Note 1 to the financial statements contained in Part II, Item 8 of this report for additional information.
[5]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606). See Note 1 to the financial statements contained in Part II, Item 8 of this report for additional information.
[6]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606). See Note 1 to the financial statements contained in Part II, Item 8 of this report for additional information.
[7]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606). See Note 1 to the financial statements contained in Part II, Item 8 of this report for additional information.
[8]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606) and Accounting Standards Update No. 2017-07, Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost. See Note 1 to the financial statements contained in Part II, Item 8 of this report for additional information.

Statements of Consolidated Stockholder's Equity - USD ($)
$ in Millions

Total

United Airlines, Inc.

Common Stock

Additional Capital Invested

United Airlines, Inc.

Treasury Stock

Retained Earnings (Accumulated Deficit)

United Airlines, Inc.

Accumulated Other Comprehensive Income (Loss)

United Airlines, Inc.

Receivable from Related Parties, Net

United Airlines, Inc.

Balance (in shares) at Dec. 31, 2015

364,600,000

Balance at Dec. 31, 2015

$ 8,966

$ 8,963

$ 4

$ 7,946

$ 6,138

$ (1,610)

$ 3,457

$ 3,673

$ (831)

$ (17)

Other comprehensive income (loss)

2,234

^{[1],[2],[3],[4]}

2,234

^[5],[6],[7]

2,234

^[4]

2,234

^[7],[8]

^[5]

Stock-settled share-based compensation

Proceeds from exercise of stock options / net treasury stock issued for share-based awards (in shares)

(2,603)

300,000

Proceeds from exercise of stock options

Repurchases of common stock (in shares)

(50,300,000)

UAL contribution related to stock plans

(2,607)

Treasury stock retired

$ (1)

(1,415)

3,709

(2,293)

Balance (in shares) at Dec. 31, 2016

(59)

(114)

(3)

(56)

(58)

314,600,000

Balance at Dec. 31, 2016

8,574

8,520

$ 3

6,569

3,573

(511)

3,342

5,851

(829)

(75)

Other comprehensive income (loss)

2,144

^{[1],[2],[3],[4]}

2,163

^[5],[6],[7]

2,144

^[4]

2,163

^[7],[8]

(200)

^[5]

(200)

Stock-settled share-based compensation

Proceeds from exercise of stock options / net treasury stock issued for share-based awards (in shares)

(1,844)

200,000

Proceeds from exercise of stock options

Repurchases of common stock (in shares)

(27,800,000)

Net treasury stock issued for share-based awards

(1,844)

Treasury stock retired

(508)

1,576

(1,068)

$ (12)

(21)

(1)

UAL contribution related to stock plans

Reclassification of stranded tax effects

118

(118)

Balance (in shares) at Dec. 31, 2017

$ (15)

(15)

286,973,195

^[9]

1,000

^[10]

287,000,000

Balance at Dec. 31, 2017

$ 8,734

^[9]

$ 8,696

^[10]

$ 3

6,098

1,787

(769)

4,549

8,146

(1,147)

(90)

Other comprehensive income (loss)

2,129

2,131

2,129

2,131

338

Stock-settled share-based compensation

$ 60

Proceeds from exercise of stock options / net treasury stock issued for share-based awards (in shares)

(1,249)

400,000

Repurchases of common stock (in shares)

(17,500,000)

Net treasury stock issued for share-based awards

$ (1,250)

(1,250)

$ (16)

(38)

(4)

Balance (in shares) at Dec. 31, 2018

$ (19)

(5)

(20)

269,914,769

1,000

269,900,000

Balance at Dec. 31, 2018

$ 9,995

$ 9,957

$ 3

$ 6,120

$ 598

$ (1,993)

$ 6,668

$ 10,272

$ (803)

$ (110)

[1]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606) and Accounting Standards Update No. 2017-07, Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost. See Note 1 to the financial statements contained in Part II, Item 8 of this report for additional information.
[2]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606). See Note 1 to the financial statements contained in Part II, Item 8 of this report for additional information.
[3]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606). See Note 1 to the financial statements contained in Part II, Item 8 of this report for additional information.
[4]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606). See Note 1 to the financial statements contained in Part II, Item 8 of this report for additional information.
[5]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606). See Note 1 to the financial statements contained in Part II, Item 8 of this report for additional information.
[6]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606). See Note 1 to the financial statements contained in Part II, Item 8 of this report for additional information.
[7]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606). See Note 1 to the financial statements contained in Part II, Item 8 of this report for additional information.
[8]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606) and Accounting Standards Update No. 2017-07, Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost. See Note 1 to the financial statements contained in Part II, Item 8 of this report for additional information.
[9]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606). See Note 1 to the financial statements contained in Part II, Item 8 of this report for additional information.
[10]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606). See Note 1 to the financial statements contained in Part II, Item 8 of this report for additional information.

Significant Accounting Policies

12 Months Ended

Dec. 31, 2018

Accounting Policies [Abstract]

Significant Accounting Policies

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— The Company presents Passenger revenue, Cargo revenue and Other operating revenue on its income statement. 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 mainline and regional 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. The Company records breakage revenue on the travel date for its estimate of tickets that will expire unused. To determine breakage, the Company uses its historical experience with refundable and nonrefundable expired tickets and other facts, such as recent aging trends, program changes and modifications that could affect the ultimate expiration patterns of tickets. Fees charged in association with changes or extensions to non-refundable tickets are considered part of the Company's passenger travel obligation. As such, those fees are deferred at the time of collection and recognized at the time the travel is provided.

United initially capitalizes the costs of selling airline travel tickets and then recognizes those costs as Distribution expense at the time of travel. Passenger ticket costs 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. In the years ended December 31, 2018 and 2017, the Company recognized approximately $3.1 billion and $2.9 billion, respectively, of passenger revenue for tickets that were included in Advance ticket sales at the beginning of those periods. All tickets sold at any given point of time have travel dates extending up to twelve months. As a result, the balance of the Company's Advance ticket sales liability represents activity that will be recognized in the next twelve months.


	Revenue by Geography. The Company further disaggregates revenue by geographic regions. 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.

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. Managing the Company as one segment allows management the opportunity to maximize the value of its route network.

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):



	2018		2017¹		2016¹
Domestic (U.S. and Canada)	$	25,552	$	23,114	$	22,151
Atlantic	7,103		6,340		6,194
Pacific	5,188		4,914		4,984
Latin America	3,460		3,416		3,229
Total	$	41,303	$	37,784	$	36,558

(1) Amounts adjusted due to the adoption of Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606). See (u) below for additional information.

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 dedicated 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.

Ancillary Fees. The Company charges fees, separately from ticket sales, for certain ancillary services that are directly related to passengers' travel, such as ticket change fees, baggage fees, inflight amenities 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 $2.2 billion, $2.0 billion, and $1.9 billion of ancillary fees within passenger revenue in the years ended December 31, 2018, 2017 and 2016 respectively.

(c)

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 the goods and services of our network of non-airline partners. We have contracts to sell miles to these partners with the terms extending from one to eight 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 expire after 18 months of member account inactivity.

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.

The Company's estimated selling price of miles is based on an equivalent ticket value less breakage, 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. The Company reviews its breakage estimates annually based upon the latest available information regarding redemption and expiration patterns. The Company's estimate of the expected expiration of miles requires significant management judgment. Current and future changes to expiration assumptions or to the expiration policy, 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 significant contract (the "Co-Brand Agreement") to sell MileagePlus miles to its co-branded credit card partner 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.


•	Marketing – United has a performance obligation to provide Chase access to its customer list and the use of its 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 (including monthly and one-time payments) 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 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 table below presents a roll forward of Frequent flyer deferred revenue (in millions):



	Twelve Months Ended December 31,
	2018			2017
Total Frequent flyer deferred revenue - beginning balance	$	4,783		$	4,889
Total miles awarded	2,451			2,077
Travel miles redeemed (Passenger revenue)	(2,068		)	(2,004		)
Non-travel miles redeemed (Other operating revenue)	(161		)	(179		)
Total Frequent flyer deferred revenue - ending balance	$	5,005		$	4,783

In the year ended December 31, 2018, 2017 and 2016, the Company recognized, in Other operating revenue, $2.0 billion, $1.8 billion and $1.7 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 Chase co-brand agreement. The portion related to the MileagePlus miles awarded of the total amounts received is deferred and presented in the table above as an increase to the frequent flyer liability.


(d)	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 primarily includes cash collateral for letters of credit and collateral associated with obligations for facility leases and other insurance-related obligations. 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.

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):



	UAL						United
	At December 31,						At December 31,
	2018		2017		2016		2018		2017		2016
Current assets:
Cash and cash equivalents	$	1,694	$	1,482	$	2,179	$	1,688	$	1,476	$	2,173
Restricted cash included in Prepaid expenses and other	—		18		—		—		18		—
Other assets:
Restricted cash	105		91		124		105		91		124
Total cash, cash equivalents and restricted cash shown in the statement of consolidated cash flows	$	1,799	$	1,591	$	2,303	$	1,793	$	1,585	$	2,297

(e)

Short-term Investments—Debt investments 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 securities are reflected as a component of accumulated other comprehensive income (loss). Equity investments with readily determinable fair values are measured at fair value. Equity investments without readily determinable fair values are measured using the equity method, or measured at cost with adjustments for observable changes in price or impairments (referred to as the measurement alternative). Changes in fair value are recorded in Miscellaneous, net in the consolidated statements of operations.

(f)

Accounts Receivable. Accounts receivable primarily consist of amounts due from credit card companies, non-airline partners, and cargo transportation customers. We provide an allowance for uncollectible accounts equal to the estimated losses expected to be incurred based on historical write-offs and other specific analyses. Bad debt expense and write-offs were not material for the year ended December 31, 2018 and 2017.


(g)	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.

(h)

Property and Equipment—The Company records additions to owned operating property and equipment at cost when acquired. Property under capital 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. It is the Company's policy to record compensation from delays in delivery of aircraft as a reduction of the cost of the related aircraft.

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 assured at key airports, or the estimated useful life of the related asset, whichever is less. Properties under capital leases are amortized on 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 capital 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 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, 2018 and 2017, the Company had a carrying value of computer software of $359 million and $345 million, respectively. For the years ended December 31, 2018, 2017 and 2016, the Company's depreciation expense related to computer software was $122 million, $117 million and $108 million, respectively. Aircraft and aircraft spare 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.

(i)

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.


(j)	Lease Fair Value Adjustments—Lease fair value adjustments, which arose from recording operating leases at fair value under fresh start or business combination accounting, are amortized on a straight-line basis over the related lease term.


(k)	Regional Capacity Purchase—Payments made to regional carriers under capacity purchase agreements ("CPAs") are reported in Regional capacity purchase in our consolidated statements of operations.


(l)	Advertising—Advertising costs, which are included in Other operating expenses, are expensed as incurred. Advertising expenses were $211 million, $217 million and $220 million for the years ended December 31, 2018, 2017 and 2016 respectively.

(m)

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 annually or more frequently if events or circumstances indicate that the asset may be impaired. Goodwill and indefinite-lived assets are reviewed for impairment on an annual basis as of October 1, or on an interim basis whenever a triggering event occurs. See Note 2 of this report for additional information related to intangibles.

(n)

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. An impairment charge is recognized when the asset's carrying value exceeds its net undiscounted future cash flows and its fair market value. The amount of the charge is the difference between the asset's carrying value and fair market value. See Note 14 of this report for additional information related to asset impairments.

(o)

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 both UAL's stock price and the then current level of expected performance achievement for the performance-based awards. See Note 5 of this report for additional information on UAL's share-based compensation plans.


(p)	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.

(q)

Retirement of Leased Aircraft—The Company accrues for estimated lease costs over the remaining term of the lease at the present value of future minimum lease payments, net of estimated sublease rentals (if any), in the period that aircraft are permanently removed from service. When reasonably estimable and probable, the Company estimates maintenance lease return condition obligations for items such as minimum aircraft and engine conditions specified in leases and accrues these amounts over the lease term while the aircraft are operating, and any remaining unrecognized estimated obligations are accrued in the period that an aircraft is removed from service.

(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 has 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 7 of this report for additional information on UAL's uncertain tax positions.

(s)

Labor Costs—The Company records expenses associated with amendable labor agreements when the amounts are probable and estimable. These include costs associated with lump sum cash payments that would be 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.

(t)

Third-Party Business—The Company has third-party business revenue that includes fuel sales, catering, ground handling, maintenance services and frequent flyer award non-air redemptions. Third-party business revenue is recorded in Other operating revenue. The Company also incurs third-party business expenses, such as maintenance, ground handling and catering services for third parties, fuel sales and non-air mileage redemptions. The third-party business expenses are recorded in Other operating expenses, except for non-air mileage redemption. Non-air mileage redemption expenses are recorded to Other operating revenue.

(u)

Recently Issued Accounting Standards— The Company adopted Financial Accounting Standards Board ("FASB") Accounting Standards Codification Topic 606, Revenue from Contracts with Customers (the "New Revenue Standard"), effective January 1, 2018 using the full-retrospective method. Topic 606 prescribes that an entity should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. For the Company, the most significant impact of the standard was the reclassification of certain ancillary fees from other operating revenue into passenger revenue on the statement of consolidated operations. These ancillary fees are directly related to passenger travel, such as ticket change fees and baggage fees, and are no longer considered distinct performance obligations separate from the passenger travel component. In addition, the ticket change fees, which were previously recognized when received, are now recognized when transportation is provided. Adoption of the standard had no impact on the Company's consolidated cash flows statements.

The Company adopted Accounting Standards Update No. 2017-07, Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost (the "New Retirement Standard"), effective January 1, 2018 using the full-retrospective method. The New Retirement Standard requires employers to present the service cost component of the net periodic benefit cost in the same income statement line item as other employee compensation costs arising from services rendered during the period. The other components of net benefit cost, including interest cost, expected return on plan assets, amortization of prior service cost/credit and actuarial gain/loss, and settlement and curtailment effects, are to be presented outside of any subtotal of operating income. The Company elected to apply the practical expedient and use the amounts disclosed in Note 8 to the financial statements included in Part II, Item 8 of the Company's Annual Report on Form 10-K for the fiscal year ended December 31, 2017 as the estimation basis for applying the retrospective presentation requirements of the standard.

The New Revenue Standard and the New Retirement Standard had the same impact on the financial statements of United as they had on the financial statements of UAL. The tables below present the impact of the adoption of the New Revenue Standard and the New Retirement Standard on select accounts and captions of UAL's statements of consolidated operations for the twelve months ended December 31, 2017 and 2016 (in millions, except per share amounts) and the impact on UAL's balance sheet accounts and captions as of December 31, 2017 (in millions):



Statements of Consolidated Operations for the Years Ended December 31,
	As Previously Reported						New Revenue Standard Adjustments						New Retirement Standard Adjustments						As Adjusted
	2017			2016			2017			2016			2017			2016			2017			2016
Operating revenue:
Passenger revenue	$	32,404		$	31,457		$	2,056		$	1,972		$	—		$	—		$	34,460		$	33,429
Cargo	1,035			876			79			58			—			—			1,114			934
Other operating revenue	4,297			4,223			(2,087		)	(2,028		)	—			—			2,210			2,195
Total operating revenue	37,736			36,556			48			2			—			—			37,784			36,558
Operating expenses	34,238			32,218			(21		)	(12		)	(104		)	8			34,113			32,214
Operating income	3,498			4,338			69			14			104			(8		)	3,671			4,344
Nonoperating expense, net	(499		)	(519		)	(28		)	(60		)	(104		)	8			(631		)	(571		)
Income before income taxes	2,999			3,819			41			(46		)	—			—			3,040			3,773
Income tax expense	868			1,556			28			(17		)	—			—			896			1,539
Net income	$	2,131		$	2,263		$	13		$	(29	)	$	—		$	—		$	2,144		$	2,234

Earnings per share, basic	$	7.04		$	6.86		$	0.04		$	(0.09	)	$	—		$	—		$	7.08		$	6.77
Earnings per share, diluted	$	7.02		$	6.85		$	0.04		$	(0.09	)	$	—		$	—		$	7.06		$	6.76



Consolidated Balance Sheet as of December 31, 2017
	As Previously Reported		New Revenue Standard Adjustments			As Adjusted
Current assets:
Prepaid expenses and other	$	1,051	$	20		$	1,071
Current liabilities:
Advance ticket sales	3,876		64			3,940
Frequent flyer deferred revenue	2,176		16			2,192
Other	569		7			576
Other liabilities and deferred credits:
Frequent flyer deferred revenue	2,565		26			2,591
Deferred income taxes	225		(21		)	204
Stockholders' equity:
Retained earnings	$	4,621	$	(72	)	$	4,549

The Company adopted Accounting Standards Update No. 2016-01, Financial Instruments—Overall (Subtopic 825-10) effective January 1, 2018. This standard made several changes, including the elimination of the available-for-sale classification of equity investments, and requires equity investments with readily determinable fair values to be measured at fair value with changes in fair value recognized in earnings. The Company reclassified to retained earnings $6 million of unrealized loss, net of tax, on the Company's investment in Azul, S.A. ("Azul") which was previously classified as an available-for-sale security. See Notes 6 and 9 to the financial statements included in this Part II, Item 8 for additional information.

In June 2016, the FASB issued Accounting Standards Update No. 2016-13, Financial Instruments—Credit Losses ("ASU 2016-13"). The main objective is to provide financial statement users with more decision-useful information about the expected credit losses on financial instruments and other commitments to extend credit held by a reporting entity at each reporting date. The amendments in this update replace the incurred loss methodology with a methodology that reflects expected credit losses and requires consideration of a broader range of reasonable and supportable information to calculate credit loss estimates. For trade receivables, loans and held-to-maturity debt securities, entities will be required to estimate lifetime expected credit losses. For available-for-sale debt securities, entities will be required to recognize an allowance for credit losses rather than a reduction to the carrying value of the asset. The amendments are effective for public business entities for fiscal years and interim periods beginning after December 15, 2019. The Company is evaluating the impact the adoption of ASU 2016-13 will have on its consolidated financial statements and believes that it will not have a material impact on its consolidated financial statements.

In 2016, the FASB amended the FASB Accounting Standards Codification and created a new Topic 842, Leases (the "New Lease Standard"). The guidance requires lessees to recognize a right-of-use asset and a lease liability for all leases (with the exception of short-term leases) at the commencement date and recognize expenses on their income statements similar to the current Topic 840, Leases ("Topic 840"). The New Lease Standard is effective for fiscal years and interim periods beginning after December 15, 2018. The Company adopted this standard on January 1, 2019 using a modified retrospective approach for all leases existing at or commencing after the date of initial application and utilizing certain practical expedients.

The adoption of the New Lease Standard is expected to impact our reported results as shown in the tables below (in millions, except per share amounts):



Consolidated Balance Sheets as of December 31,
	As Reported						New Lease Standard Adjustments						As Adjusted
	2018			2017			2018			2017			2018			2017
Current assets:
Receivables, less allowance for doubtful accounts	$	1,346		$	1,340		$	80		$	126		$	1,426		$	1,466
Prepaid expenses and other	913			1,071			(180		)	(208		)	733			863

Operating property and equipment:
Other property and equipment (owned)	7,919			6,946			(1,041		)	(922		)	6,878			6,024
Less-Accumulated depreciation and amortization (owned)	(12,760		)	(11,159		)	140			92			(12,620		)	(11,067		)
Flight equipment (finance leases) (a)	1,029			1,151			(37		)	(211		)	992			940
Less-Accumulated amortization	(654		)	(777		)	8			169			(646		)	(608		)

Operating lease assets
Flight equipment	—			—			2,380			3,102			2,380			3,102
Other property and equipment	—			—			2,882			2,975			2,882			2,975

Current liabilities:
Current maturities of finance leases (a)	149			128			(26		)	(50		)	123			78
Current maturities of operating leases	—			—			719			949			719			949
Other	619			576			(66		)	(58		)	553			518

Long-term obligations under finance leases (a)	1,134			996			(910		)	(766		)	224			230
Long-term obligations under operating leases	—			—			5,276			5,789			5,276			5,789

Other liabilities and deferred credits:
Deferred income taxes	814			204			14			16			828			220
Other	1,832			1,832			(822		)	(811		)	1,010			1,021

Stockholders' equity:
Retained earnings	6,668			4,549			47			54			6,715			4,603

(a) Finance leases, under the New Lease Standard, are the equivalent of capital leases under Topic 840.

The adoption of the New Lease Standard primarily resulted in the recording of assets and obligations of our operating leases on our consolidated balance sheets. Certain amounts recorded for prepaid and accrued rent associated with historical operating leases were reclassified to the newly captioned Operating lease assets in the consolidated balance sheets. Also, certain leases designated under Topic 840 as owned assets and capitalized finance leases will not be considered assets under the New Lease Standard and will be removed from the consolidated balance sheets, along with the related capital lease liability.



Statements of Consolidated Operations for the Years Ended December 31,
	As Reported						New Lease Standard Adjustments						As Adjusted
	2018			2017			2018			2017			2018			2017
Operating expense:
Regional capacity purchase	$	2,601		$	2,232		$	48		$	36		$	2,649		$	2,268
Landing fees and other rent	2,359			2,240			90			70			2,449			2,310
Depreciation and amortization	2,240			2,149			(75		)	(53		)	2,165			2,096
Total operating expenses	38,011			34,113			63			53			38,074			34,166
Operating income	3,292			3,671			(63		)	(53		)	3,229			3,618

Nonoperating income (expense):
Interest expense	(729		)	(671		)	59			45			(670		)	(626		)
Interest capitalized	70			84			(5		)	(10		)	65			74
Total nonoperating expense, net	(634		)	(631		)	53			36			(581		)	(595		)
Income before income taxes	2,658			3,040			(10		)	(17		)	2,648			3,023
Income tax expense	529			896			(3		)	(16		)	526			880
Net income	$	2,129		$	2,144		$	(7	)	$	(1	)	$	2,122		$	2,143
Earnings per share, basic	$	7.73		$	7.08		$	(0.03	)	$	—		$	7.70		$	7.08
Earnings per share, diluted	$	7.70		$	7.06		$	(0.03	)	$	—		$	7.67		$	7.06

The expense for leases under the New Lease Standard will continue to be classified in their historical income statement captions (primarily in Aircraft rent, Landing fees and other rent and Regional capacity purchase in our statements of consolidated operations). The adoption of the New Lease Standard also resulted in the recharacterization of certain leases from capital leases under Topic 840 to operating leases under the New Lease Standard. This change will result in less depreciation and amortization and interest expense associated with capital leases offset by higher lease expense associated with operating leases. The change is associated with leases of aircraft under certain CPAs and certain airport facilities. The reduction in capitalized interest is also associated with the same airport facilities.

Goodwill and Other Intangible Assets

12 Months Ended

Dec. 31, 2018

Goodwill and Intangible Assets Disclosure [Abstract]

Goodwill and Other Intangible Assets

GOODWILL AND OTHER INTANGIBLE ASSETS

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



	2018				2017
Item	Gross Carrying Amount		Accumulated Amortization		Gross Carrying Amount		Accumulated Amortization
Goodwill	$	4,523			$	4,523

Finite-lived intangible assets
Frequent flyer database	$	1,177	$	884	$	1,177	$	832
Hubs	145		97		145		89
Contracts	120		106		121		103
Patents and tradenames	108		108		108		108
Airport slots and gates	97		97		97		97
Other	109		88		109		84
Total	$	1,756	$	1,380	$	1,757	$	1,313
Indefinite-lived intangible assets
Route authorities	$	1,240			$	1,562
Airport slots and gates	546				536
Tradenames and logos	593				593
Alliances	404				404
Total	$	2,783			$	3,095

Amortization expense in 2018, 2017 and 2016 was $67 million, $79 million and $90 million, respectively. Projected amortization expense in 2019, 2020, 2021, 2022 and 2023 is $61 million, $55 million, $50 million, $40 million and $37 million, respectively.

See Note 14 of this report for additional information related to impairment of intangible assets.

- Definition

The entire disclosure for the aggregate amount of goodwill and a description of intangible assets, which may include (a) for amortizable intangible assets (also referred to as finite-lived intangible assets), the carrying amount, the amount of any significant residual value, and the weighted-average amortization period, (b) for intangible assets not subject to amortization (also referred to as indefinite-lived intangible assets), the carrying amount, and (c) the amount of research and development assets acquired and written off in the period, including the line item in the income statement in which the amounts written off are aggregated, if not readily apparent from the income statement. Also discloses (a) for amortizable intangibles assets in total and by major class, the gross carrying amount and accumulated amortization, the total amortization expense for the period, and the estimated aggregate amortization expense for each of the five succeeding fiscal years, (b) for intangible assets not subject to amortization the carrying amount in total and by major class, and (c) for goodwill, in total and for each reportable segment, the changes in the carrying amount of goodwill during the period (including the aggregate amount of goodwill acquired, the aggregate amount of impairment losses recognized, and the amount of goodwill included in the gain (loss) on disposal of a reporting unit). If any part of goodwill has not been allocated to a reportable segment, discloses the unallocated amount and the reasons for not allocating. For each impairment loss recognized related to an intangible asset (excluding goodwill), discloses: (a) a description of the impaired intangible asset and the facts and circumstances leading to the impairment, (b) the amount of the impairment loss and the method for determining fair value, (c) the caption in the income statement or the statement of activities in which the impairment loss is aggregated, and (d) the segment in which the impaired intangible asset is reported. For each goodwill impairment loss recognized, discloses: (a) a description of the facts and circumstances leading to the impairment, (b) the amount of the impairment loss and the method of determining the fair value of the associated reporting unit, and (c) if a recognized impairment loss is an estimate not finalized and the reasons why the estimate is not final. May also disclose the nature and amount of any significant adjustments made to a previous estimate of an impairment loss.

+ References + Details

Common Stockholders' Equity and Preferred Securities	12 Months Ended
Common Stockholders' Equity and Preferred Securities	Dec. 31, 2018
Equity [Abstract]
Common Stockholders' Equity and Preferred Securities	COMMON STOCKHOLDERS' EQUITY AND PREFERRED SECURITIES In 2018, UAL repurchased approximately 17.5 million shares of UAL common stock for $1.2 billion. In December 2017, UAL's Board of Directors authorized a $3.0 billion share repurchase program to acquire UAL's common stock. As of December 31, 2018, the Company had approximately $1.8 billion remaining to purchase shares under its share repurchase program. UAL may repurchase shares through the open market, privately negotiated transactions, block trades or accelerated share repurchase transactions from time to time in accordance with applicable securities laws. UAL may repurchase shares of UAL common stock subject to prevailing market conditions, and may discontinue such repurchases at any time. See Part II, Item 5, Market for registrant's common equity, related stockholder matters and issuer purchases of equity securities, of this report for additional information. At December 31, 2018, approximately 10 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, 2018, 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.

Earnings Per Share

12 Months Ended

Dec. 31, 2018

Earnings Per Share [Abstract]

Earnings Per Share

EARNINGS PER SHARE

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



	2018		2017 (a)		2016 (a)
Earnings available to common stockholders	$	2,129	$	2,144	$	2,234

Basic weighted-average shares outstanding	275.5		302.7		329.9
Effect of employee stock awards	1.2		0.9		0.4
Diluted weighted-average shares outstanding	276.7		303.6		330.3

Earnings per share, basic	$	7.73	$	7.08	$	6.77
Earnings per share, diluted	$	7.70	$	7.06	$	6.76

(a) Amounts adjusted due to the adoption of Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606). See Note 1 to the financial statements contained in Part II, Item 8 of this report for additional information.

The number of antidilutive securities excluded from the computation of diluted earnings per share amounts was not material.

Share-Based Compensation Plans

12 Months Ended

Dec. 31, 2018

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Share-Based Compensation Plans

SHARE-BASED COMPENSATION PLANS

UAL maintains several share-based compensation plans. These plans provide for grants of non-qualified stock options, incentive stock options (within the meaning of Section 422 of the Internal Revenue Code of 1986), stock appreciation rights, restricted shares, RSUs, performance compensation awards, performance units, cash incentive awards, other equity-based and equity-related awards, and dividends and 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 2018, UAL granted share-based compensation awards pursuant to the United Continental Holdings, Inc. 2017 Incentive Compensation Plan. These share-based compensation awards included approximately 1.8 million RSUs consisting of 1.1 million time-vested RSUs and 0.7 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. These 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 performance-based RSUs vest based on the Company's relative improvement in pre-tax margin compared to a group of airline industry peers for the three years ending December 31, 2020. If the performance condition is achieved, cash payments will be made after the end of the performance period based on the 20-day average closing price of UAL common stock immediately prior to the vesting date and based on the level, if any, of the performance goal achieved. The Company accounts for the performance-based RSUs as liability awards.

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



	2018		2017		2016
Compensation cost:
RSUs	$	98	$	63	$	58
Restricted stock	2		8		11
Stock options	1		2		1
Total	$	101	$	73	$	70

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, 2018 (in millions, except as noted):

RSUs and Restricted Stock. All performance-based RSUs, as well as a portion of the outstanding time-vested RSUs, will be settled in cash. As of December 31, 2018, UAL had recorded a liability of $51 million related to its RSUs. UAL paid $28 million, $50 million and $69 million related to its RSUs during 2018, 2017 and 2016, respectively.

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



	Liability Awards		Equity Awards
	RSUs		RSUs		Weighted- Average Grant Price		Restricted Stock		Weighted- Average Grant Price
Outstanding at December 31, 2015	2.6		—		$	—	0.3		$	48.68
Granted	1.0		0.9		51.60		0.4		50.63
Vested	(1.4	)	—		—		(0.1	)	41.47
Forfeited	(0.1	)	(0.1	)	50.57		(0.1	)	53.42
Outstanding at December 31, 2016	2.1		0.8		51.67		0.5		52.00
Granted	0.6		1.0		71.68		—		—
Vested	(0.7	)	(0.3	)	51.81		(0.2	)	51.60
Forfeited	(0.2	)	(0.1	)	57.49		—		—
Outstanding at December 31, 2017	1.8		1.4		63.99		0.3		52.30
Granted	0.7		1.1		67.74		—		—
Vested	(0.5	)	(0.5	)	63.02		(0.2	)	53.24
Forfeited	(0.1	)	(0.2	)	67.34		—		—
Outstanding at December 31, 2018	1.9		1.8		66.29		0.1		51.17

The fair value of RSUs and restricted stock that vested in 2018, 2017 and 2016 was $70 million, $76 million and $80 million, respectively. The fair value of the restricted stock and the stock-settled RSUs was based upon the UAL common stock price on the date of grant. These awards are accounted for as equity awards. The fair value of the cash-settled RSUs was based on the UAL common stock price as of the last day preceding the settlement date. These awards are accounted for as liability awards. Restricted stock vesting and the recognition of the expense is similar to the stock option vesting described below.

Stock Options. During 2018, UAL did not grant any stock option awards. In 2017, UAL granted approximately 36,000 stock options with exercise prices equal to the fair market value of UAL's common stock on the date of grant with a weighted-average exercise price of $77.56 and a weighted-average grant date fair value of approximately $0.7 million. In 2016, UAL granted approximately 0.1 million stock options with exercise prices equal to the fair market value of UAL's common stock on the date of grant and an additional approximately 0.3 million stock options with exercise prices at a 25% premium of the grant date fair market value resulting in a weighted-average exercise price of $56.19 and a weighted-average grant date fair value of approximately $2.3 million. Expense related to each portion of an option grant is recognized on a straight-line basis over the specific vesting period for those options.

The Company determined the grant date fair value of stock options using a Black-Scholes option pricing model, which requires the use of several assumptions. The risk-free interest rate is based on the U.S. treasury yield curve in effect for the expected term of the option at the time of grant. The dividend yield on UAL's common stock was assumed to be zero since UAL did not have any plans to pay dividends at the time of the option grants. The volatility assumptions were based upon historical volatilities of UAL using daily stock price returns equivalent to the expected term of the option. The expected term of the options was determined based upon a simplified assumption that the option will be exercised evenly from vesting to expiration due to the Company's lack of relevant historical data related to stock options.

As of December 31, 2018, there were approximately 0.4 million outstanding stock option awards, 0.2 million of which were exercisable, with weighted-average exercise prices of $55.62 and $47.07, respectively, intrinsic values of $12 million and $6 million, respectively, and weighted-average remaining contractual lives (in years) of 5.8 and 3.8, respectively.

Accumulated Other Comprehensive Income (Loss)

12 Months Ended

Dec. 31, 2018

Equity [Abstract]

Accumulated Other Comprehensive Income (Loss)

ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS)

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



	Pension and Other Postretirement Liabilities				Fuel Derivatives Contracts			Investments and Other			Deferred Taxes				Total
Balance at December 31, 2015	$	(363	)		$	(215	)	$	3		$	(256	)		$	(831	)
Other comprehensive income (loss) before reclassifications	(517		)	(a)	(4		)	—			187				(334		)
Amounts reclassified from accumulated other comprehensive income	26				217			(2		)	95				336
Balance at December 31, 2016	(854		)		(2		)	1			26				(829		)
Other comprehensive income (loss) before reclassifications	(306		)	(a)	—			(7		)	74				(239		)
Amounts reclassified from accumulated other comprehensive income	58				2			—			(21		)		39
Reclassification of stranded tax effects	—				—			—			(118		)	(b)	(118		)
Balance at December 31, 2017	(1,102		)		—			(6		)	(39		)		(1,147		)
Other comprehensive income (loss) before reclassifications	377			(a)	—			(5		)	(83		)		289
Amounts reclassified from accumulated other comprehensive income	62				—			—			(13		)		49
Amounts reclassified to retained earnings	—				—			7			(1		)		6
Balance at December 31, 2018	$	(663	)		$	—		$	(4	)	$	(136	)		$	(803	)



Details about AOCI Components	Amount Reclassified from AOCI to Income							Affected Line Item in the Statement Where Net Income is Presented
	Year Ended December 31,
	2018		2017		2016
Fuel derivative contracts
Fuel contracts-reclassifications of losses into earnings	$	—	$	2	$	217		Aircraft fuel
Pension and Postretirement liabilities and other
Amortization of unrecognized (gains) losses and prior service cost (c)	62		58		26			Miscellaneous, net
Investments and other
Available-for-sale securities - reclassifications of gains into earnings	—		—		(2		)	Miscellaneous, net

(a) Prior service credits decreased by $3 million, $0 million and increased by $30 million and actuarial losses decreased by approximately $380 million, and increased $306 million and $560 million for 2018, 2017 and 2016, respectively.

(b) This amount represents the reclassification from AOCI to RE of the stranded tax effects resulting from the enactment of the Tax Cuts and Jobs Act (the "Tax Act").

(c) This AOCI component is included in the computation of net periodic pension and other postretirement costs (see Note 8 of this report for additional information).

Income Taxes

12 Months Ended

Dec. 31, 2018

Income Tax Disclosure [Abstract]

Income Taxes

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, as follows (in millions):



UAL	2018			2017 (a)			2016 (a)
Income tax provision at statutory rate	$	558		$	1,064		$	1,320
State income taxes, net of federal income tax benefit	29			30			38
Foreign tax rate differential	(84		)	(43		)	—
Global intangible low-taxed income	4			—			—
Foreign income taxes	2			3			3
Nondeductible employee meals	12			17			16
Impact of Tax Act	(5		)	(179		)	—
Income tax adjustment from AOCI (b)	—			—			180
State rate change	3			12			(12		)
Valuation allowance	(3		)	(16		)	20
Other, net	13			8			(26		)
	$	529		$	896		$	1,539

Current	$	14		$	(77	)	$	(92	)
Deferred	515			973			1,631
	$	529		$	896		$	1,539

United	2018			2017 (a)			2016 (a)
Income tax provision at statutory rate	$	559		$	1,065		$	1,321
State income taxes, net of federal income tax	29			30			38
Foreign tax rate differential	(84		)	(43		)	—
Global intangible low-taxed income	4			—			—
Foreign income taxes	2			3			3
Nondeductible employee meals	12			17			16
Impact of Tax Act	(5		)	(196		)	—
Income tax adjustment from AOCI (b)	—			—			180
State rate change	3			12			(12		)
Valuation allowance	(3		)	(16		)	20
Other, net	12			7			(25		)
	$	529		$	879		$	1,541

Current	$	14		$	(77	)	$	(92	)
Deferred	515			956			1,633
	$	529		$	879		$	1,541

(b) Prior to the release of the deferred income tax valuation allowance in the third quarter of 2015, the Company recorded approximately $465 million of valuation allowance adjustments in AOCI. Subsequent to the release of the deferred income tax valuation allowance in 2015, the $465 million debit remained within AOCI, of which $180 million related to losses on fuel hedges designated for hedge accounting and $285 million related to pension and other postretirement liabilities. Accounting rules required the adjustments to remain in AOCI as long as the Company had fuel derivatives designated for cash flow hedge accounting and the Company continues to provide pension and postretirement benefits. In 2016, the Company settled all of its fuel hedges and has not entered into any new fuel derivative contracts for hedge accounting. Accordingly, the Company reclassified the $180 million to income tax expense in 2016.

The Company's effective tax rate for the year ended December 31, 2018 differed from the federal statutory rate of 21% due to a blend of federal, state and foreign taxes as well as the impact of certain nondeductible items.

On December 22, 2017, Congress enacted the Tax Act, which made significant changes to U.S. federal income tax laws, including reducing the corporate rate from 35% to 21% effective January 1, 2018. In December 2017, the SEC issued Staff Accounting Bulletin No. 118 ("SAB 118"), which allowed the Company to record provisional amounts related to the impact of the Tax Act and to adjust those amounts during a measurement period not to extend more than one year from the date of enactment. Based on our current interpretation of the Tax Act and published Treasury and Internal Revenue Service ("IRS") guidance as of December 31, 2018, the Company's accounting for the impacts of the Tax Act is complete and the Company has not recorded any material adjustments to the provisional amounts under SAB 118. In 2018, we recorded an income tax benefit for the one-time transition tax of $4 million and have completed the re-measurement of our net deferred tax balances. The Tax Act included a Global Intangible Low-Taxed Income ("GILTI") provision which introduced a new tax on foreign income in excess of a deemed return on tangible business property of foreign subsidiaries. The GILTI provisions of the Tax Act became effective for the Company during 2018 and we elected to account for it in the period incurred (the "period cost method").

Temporary differences and carryforwards that give rise to deferred tax assets and liabilities at December 31, 2018 and 2017 were as follows (in millions):



	UAL						United
	2018			2017			2018			2017
Deferred income tax asset (liability):
Federal and state net operating loss ("NOL") carryforwards	$	398		$	601		$	372		$	574
Deferred revenue	1,232			1,090			1,232			1,090
Employee benefits, including pension, postretirement and medical	885			1,051			885			1,051
Other	408			351			406			351
Less: Valuation allowance	(59		)	(63		)	(59		)	(63		)
Total deferred tax assets	$	2,864		$	3,030		$	2,836		$	3,003

Depreciation	$	(2,929	)	$	(2,431	)	$	(2,929	)	$	(2,431	)
Intangibles	(749		)	(803		)	(749		)	(803		)
Total deferred tax liabilities	$	(3,678	)	$	(3,234	)	$	(3,678	)	$	(3,234	)
Net deferred tax liability	$	(814	)	$	(204	)	$	(842	)	$	(231	)

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 liability 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 only if they would be able to use those benefits on a separate company basis.

The Company's federal and state NOL carryforwards relate to prior years' NOLs, which may be used to reduce tax liabilities in future years. These tax benefits are mostly attributable to federal pre-tax NOL carryforwards of $1.6 billion for UAL. If not utilized these federal pre-tax NOLs will expire as follows (in billions): $0.6 in 2030, $1.0 thereafter. In addition, for UAL the majority of tax benefits of the state NOLs of $83 million will expire over a five to twenty year period. We have recorded a $48 million valuation allowance against these state NOLs.

The Company's unrecognized tax benefits related to uncertain tax positions were $39 million, $21 million and $74 million at December 31, 2018, 2017 and 2016, respectively. Included in the ending balance at December 31, 2018 is $39 million that 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 2018, 2017 and 2016. 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, 2018 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 IRS and state taxing jurisdictions. Currently, there are no ongoing examinations of the Company's prior year tax returns being conducted by the IRS.

Pension and Other Postretirement Plans

12 Months Ended

Dec. 31, 2018

Retirement Benefits [Abstract]

Pension and Other Postretirement Plans

PENSION AND OTHER POSTRETIREMENT 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 management and administrative employees. 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.

Actuarial assumption changes are reflected as a component of the net actuarial loss/(gain) during 2018 and 2017. The 2018 actuarial gains were mainly related to an increase in the discount rate applied in 2018 compared to 2017. These amounts will be amortized over the average remaining service life of the covered active employees or the average life expectancy of inactive participants. The impacts on 2018 and 2017 pension and retiree medical expense are presented below.

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, 2018			Year Ended December 31, 2017
Accumulated benefit obligation:	$	4,448		$	4,739

Change in projected benefit obligation:
Projected benefit obligation at beginning of year	$	5,852		$	5,253
Service cost	228			195
Interest cost	217			220
Actuarial (gain) loss	(601		)	525
Gross benefits paid and settlements	(292		)	(366		)
Other	(8		)	25
Projected benefit obligation at end of year	$	5,396		$	5,852

Change in plan assets:
Fair value of plan assets at beginning of year	$	3,932		$	3,355
Actual (loss) return on plan assets	(215		)	510
Employer contributions	413			419
Gross benefits paid and settlements	(292		)	(366		)
Other	(11		)	14
Fair value of plan assets at end of year	$	3,827		$	3,932
Funded status—Net amount recognized	$	(1,569	)	$	(1,920	)



	Pension Benefits
	December 31, 2018			December 31, 2017
Amounts recognized in the consolidated balance sheets consist of:
Noncurrent asset	$	13		$	9
Current liability	(6		)	(8		)
Noncurrent liability	(1,576		)	(1,921		)
Total liability	$	(1,569	)	$	(1,920	)

Amounts recognized in accumulated other comprehensive loss consist of:
Net actuarial loss	$	(1,382	)	$	(1,610	)
Prior service cost	(5		)	(1		)
Total accumulated other comprehensive loss	$	(1,387	)	$	(1,611	)

	Other Postretirement Benefits
	Year Ended December 31, 2018			Year Ended December 31, 2017
Change in benefit obligation:
Benefit obligation at beginning of year	$	1,710		$	1,687
Service cost	12			13
Interest cost	61			66
Plan participants' contributions	68			68
Benefits paid	(181		)	(178		)
Actuarial loss (gain)	(285		)	40
Other	6			14
Benefit obligation at end of year	$	1,391		$	1,710

Change in plan assets:
Fair value of plan assets at beginning of year	$	54		$	55
Actual return on plan assets	1			1
Employer contributions	111			108
Plan participants' contributions	68			68
Benefits paid	(181		)	(178		)
Fair value of plan assets at end of year	53			54
Funded status—Net amount recognized	$	(1,338	)	$	(1,656	)



	Other Postretirement Benefits
	December 31, 2018			December 31, 2017
Amounts recognized in the consolidated balance sheets consist of:
Current liability	$	(43	)	$	(54	)
Noncurrent liability	(1,295		)	(1,602		)
Total liability	$	(1,338	)	$	(1,656	)
Amounts recognized in accumulated other comprehensive income consist of:
Net actuarial gain	$	554		$	301
Prior service credit	170			208
Total accumulated other comprehensive income	$	724		$	509

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):



	2018		2017
Projected benefit obligation	$	5,196	$	5,637
Accumulated benefit obligation	4,286		4,567
Fair value of plan assets	3,614		3,709

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



	2018						2017						2016
	Pension Benefits			Other Postretirement Benefits			Pension Benefits			Other Postretirement Benefits			Pension Benefits			Other Postretirement Benefits
Service cost	$	228		$	12		$	195		$	13		$	112		$	19
Interest cost	217			61			220			66			200			86
Expected return on plan assets	(292		)	(2		)	(243		)	(2		)	(216		)	(2		)
Curtailment gain	—			—			—			—			—			(107		)
Amortization of unrecognized actuarial (gain) loss	130			(32		)	128			(33		)	76			(19		)
Amortization of prior service credits	—			(37		)	—			(37		)	—			(31		)
Other	1			—			5			—			5			—
Net periodic benefit cost (credit)	$	284		$	2		$	305		$	7		$	177		$	(54	)

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.

See Note 14 of this report for additional information related to the curtailment gain recorded in 2016.

The assumptions used for the benefit plans were as follows:



	Pension Benefits
Assumptions used to determine benefit obligations	2018		2017
Discount rate	4.20	%	3.65	%
Rate of compensation increase	3.89	%	3.89	%

Assumptions used to determine net expense
Discount rate	3.65	%	4.19	%
Expected return on plan assets	7.31	%	7.02	%
Rate of compensation increase	3.89	%	3.54	%

	Other Postretirement Benefits
Assumptions used to determine benefit obligations	2018		2017
Discount rate	4.30	%	3.63	%

Assumptions used to determine net expense
Discount rate	3.63	%	4.07	%
Expected return on plan assets	3.00	%	3.00	%
Health care cost trend rate assumed for next year	6.00	%	6.25	%
Rate to which the cost trend rate is assumed to decline (ultimate trend rate in 2023)	5.00	%	5.00	%

The Company used the Society of Actuaries' 2014 mortality tables, modified to reflect the Social Security Administration

Trustee's Report on current projections regarding expected longevity improvements.

The Company selected the 2018 discount rate for substantially all of its plans by using a hypothetical portfolio of high quality bonds at December 31, 2018, 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	30-45	%	9.5	%
Fixed-income securities	30-40		5.8
Alternatives	10-25		7.3
Other	0-10		7.8

One-hundred percent of other postretirement plan assets are invested in a deposit administration fund.

A one percentage point decrease in the weighted average discount rate would increase the Company's postretirement benefit liability by approximately $139 million and increase the estimated 2018 benefits expense by approximately $10 million.



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):



	2018										2017
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	$	1,394	$	254	$	106	$	—	$	1,034	$	1,406	$	269	$	133	$	—	$	1,004
Fixed-income securities	1,431		—		605		21		805		1,470		—		834		18		618
Alternatives	596		—		—		134		462		637		—		—		139		498
Other investments	406		224		40		142		—		419		32		124		172		91
Total	$	3,827	$	478	$	751	$	297	$	2,301	$	3,932	$	301	$	1,091	$	329	$	2,211
Other Postretirement Benefit Plan Assets:
Deposit administration fund	$	53	$	—	$	—	$	53	$	—	$	54	$	—	$	—	$	54	$	—

(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 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.

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 U.S. and non-U.S. corporate fixed-income 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 cash, insurance contracts and other funds.

The reconciliation of United's defined benefit plan assets measured at fair value using unobservable inputs (Level 3) for the years ended December 31, 2018 and 2017 is as follows (in millions):



	2018			2017
Balance at beginning of year	$	383		$	287
Actual return (loss) on plan assets:
Sold during the year	10			7
Held at year end	(21		)	16
Purchases, sales, issuances and settlements (net)	(22		)	73
Balance at end of year	$	350		$	383

Funding requirements for tax-qualified defined benefit pension plans are determined by government regulations. United's contributions reflected above have satisfied its required contributions through the 2018 calendar year. In 2019, employer anticipated contributions to all of United's pension and postretirement plans are at least $318 million and approximately $95 million, respectively.

The estimated future benefit payments, net of expected participant contributions, in United's pension plans and other postretirement benefit plans as of December 31, 2018 are as follows (in millions):



	Pension		Other Postretirement		Other Postretirement— subsidy receipts
2019	$	329	$	100	$	5
2020	327		104		6
2021	353		108		6
2022	367		111		6
2023	379		113		7
Years 2024 – 2028	2,022		575		38

Defined Contribution Plans

Depending upon the employee group, employer contributions consist of matching contributions and/or non-elective employer contributions. United's employer contribution percentages vary from 1% to 16% of eligible earnings depending on the terms of each plan. United recorded expenses for its defined contribution plans of $693 million, $656 million and $592 million in the years ended December 31, 2018, 2017 and 2016, respectively.

Multi-Employer Plans

United's participation in the IAM National Pension Plan ("IAM Plan") for the annual period ended December 31, 2018 is outlined in the table below. There have been no significant changes that affect the comparability of 2018 and 2017 contributions. 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 $435 million in employers' contributions for the year ended December 31, 2017. For 2017, the Company's contributions to the IAM Plan represented more than 5% of total contributions to the IAM Plan. The 2018 information is not available as Form 5500 is not final for the plan year.



Pension Fund	IAM National Pension Fund
EIN/ Pension Plan Number	51-6031295 - 002
Pension Protection Act Zone Status (2018 and 2017)	Green Zone. Plans in the green zone are at least 80 percent funded.
FIP/RP Status Pending/Implemented	No
United's Contributions	$52 million, $50 million and $41 million in the years ended December 31, 2018, 2017 and 2016, 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 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. 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 $334 million, $349 million and $628 million in 2018, 2017 and 2016, respectively. Profit sharing expense is recorded as a component of Salaries and related costs in the Company's statements of consolidated operations.

Investments and Fair Value Measurements

12 Months Ended

Dec. 31, 2018

Fair Value Disclosures [Abstract]

Investments and Fair Value Measurements

INVESTMENTS AND FAIR VALUE MEASUREMENTS

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 8 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):



	2018								2017
	Total		Level 1		Level 2		Level 3		Total		Level 1		Level 2		Level 3
Cash and cash equivalents	$	1,694	$	1,694	$	—	$	—	$	1,482	$	1,482	$	—	$	—
Short-term investments:
Corporate debt	1,023		—		1,023		—		958		—		958		—
Asset-backed securities	746		—		746		—		753		—		753		—
U.S. government and agency notes	108		—		108		—		113		—		113		—
Certificates of deposit placed through an account registry service ("CDARS")	75		—		75		—		120		—		120		—
Other fixed-income securities	116		—		116		—		188		—		188		—
Other investments measured at NAV	188		—		—		—		184		—		—		—
Restricted cash	105		105		—		—		109		109		—		—
Long-term investments:
Equity securities	249		249		—		—		99		99		—		—
Enhanced equipment trust certificates ("EETC")	18		—		—		18		22		—		—		22
Avianca Holdings S.A. ("AVH") Derivative Assets	11		—		—		11		—		—		—		—

Available-for-sale investment maturities - The short-term investments shown in the table above are classified as available-for-sale, with the exception of investments measured at NAV. As of December 31, 2018, asset-backed securities have remaining maturities of less than one year to approximately 16 years, corporate debt securities have remaining maturities of less than one year to approximately three years and CDARS have maturities of less than one year. U.S. government and other securities have maturities of less than one year to approximately two years. The EETC securities mature in 2019.

Restricted cash - Restricted cash primarily includes cash collateral for letters of credit and collateral associated with obligations for facility leases and other insurance-related obligations.

Equity securities - Equity securities represent United's investment in Azul. In 2018, the Company invested $138 million in Azul thus increasing its preferred equity stake in Azul to approximately 8% (representing approximately 2% of the total capital stock of Azul). The Company recognizes changes to the fair value of its equity investment in Azul in Miscellaneous, net in its statements of consolidated operations.

Synergy Term Loan - On November 29, 2018, United, as lender, entered into a Term Loan Agreement (the "Synergy Loan Agreement") with affiliates of Synergy Aerospace Corporation ("Synergy"), as borrower and guarantor, respectively, and, pursuant to the Synergy Loan Agreement, on November 30, 2018, United provided a $456 million term loan to Synergy (the "Synergy Term Loan"), secured by a pledge of borrower's equity, as well as Synergy's 516 million shares of common stock of AVH, the parent company of Avianca (equivalent to 64.5 million American Depositary Receipts ("ADRs"), the class of AVH securities that trades on the New York Stock Exchange ("NYSE")). Pursuant to the Synergy Loan Agreement, the Synergy Term Loan is due and payable in five annual installments beginning on November 30, 2021, to be repaid in full on November 30, 2025 (a portion of which is subject to extension in limited circumstances). Subject to the satisfaction of collateral coverage thresholds, minimum share price levels and certain other conditions, Synergy may repay United in shares of AVH common stock, at market value, in an amount up to 25 percent of any principal installment, or with cash from the sale of Synergy's shares of AVH stock. The Synergy Term Loan bears interest at an annual rate of 3 percent per annum, payable quarterly in arrears. United also obtained an option to acquire, on a gross or net basis and at a fixed price, up to 77.4 million shares of AVH common stock from Synergy (the "AVH Call Options"), and agreed with Synergy to share in any increase in value of the remaining 438.6 million shares of Synergy's AVH common stock within certain price ranges (the "AVH Share Appreciation Rights"). Until the third anniversary of funding, Synergy has the option to capitalize interest that would have been due, adding it to the outstanding principal balance of the Synergy Term Loan. Pursuant to the Synergy Loan Agreement, Synergy has agreed to certain financial and non-financial covenants, as well as customary events of default.

In connection with funding the Synergy Loan Agreement, on November 29, 2018, United also entered into an agreement with AVH's significant minority shareholder, Kingsland Holdings Limited ("Kingsland"), pursuant to which, in return for Kingsland's pledge of its 144.8 million shares of AVH common stock (equivalent to 18.1 million ADRs) and its consent to Synergy's pledge of its AVH common stock to United under the Synergy Loan Agreement, United (1) granted to Kingsland the right to put its shares of AVH common stock to United at market price on the fifth anniversary of the Synergy Loan Agreement, and (2) guaranteed Synergy's obligation to pay Kingsland (which amount, if paid by United, will increase United's secured loan to Synergy by such amount) if the market price of AVH common stock on the fifth anniversary is less than $12 per ADR on the NYSE, for an aggregate maximum possible combined put payment and guarantee amount on the fifth anniversary of $217.2 million. United also agreed with Kingsland to share in any increase in value of AVH common stock within certain price ranges (the "Upside Sharing Agreement").

AVH Derivative Assets - The AVH Call Options, AVH Share Appreciation Rights and the Upside Sharing Agreement (collectively, the "AVH Derivative Assets") are recorded at fair value as Other assets on the Company's balance sheet and are included in the table above. Changes in the fair value of the AVH Derivative Assets are recorded as part of Nonoperating income (expense): Miscellaneous, net on the Company's statements of consolidated operations.

Investments presented in the table above have the same fair value as their carrying value. 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, issuance costs and origination costs:



	2018										2017
	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	$	13,445	$	13,450	$	—	$	9,525	$	3,925	$	13,268	$	13,787	$	—	$	10,115	$	3,672
Synergy Term Loan	478		422		—		—		422		—		—		—		—		—

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



Description	Fair Value Methodology
Cash and cash equivalents	The carrying amounts approximate fair value because of the short-term maturity of these assets.
Short-term investments, Equity securities, EETC and Restricted cash	Fair value is based on (a) the trading prices of the investment or similar instruments, (b) an income approach, which uses valuation techniques to convert future amounts into a single present amount based on current market expectations about those future amounts when observable trading prices are not available, or (c) broker quotes obtained by third-party valuation services.
Other investments measured at NAV	In accordance with the relevant accounting standards, certain investments that are measured at fair value using the NAV per share (or its equivalent) practical expedient have not been classified in the fair value hierarchy. The fair value amounts presented in the table above are intended to permit reconciliation of the fair value hierarchy to the amounts presented in the statement of financial position. The investments measured using NAV are shares of mutual funds that invest in 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. The Company can redeem its shares at any time at NAV subject to a three-day settlement period.
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.
Synergy Term Loan and AVH Derivative Assets	Fair values are calculated using a Monte Carlo simulation approach. Unobservable inputs include expected volatility, expected dividend yield and control and acquisition premiums.

Investments in Regional Carriers. United holds investments in several regional carriers that fly for the Company as United Express under CPAs. The combined carrying value of the investments was approximately $144 million as of the date of this report. United accounts for each investment using the equity method. Each investment and United's ownership stake is listed below.


•	Republic Airways Holdings Inc. ("Republic"). United holds a 19% minority interest in Republic which the Company received in 2017 in consideration for its unsecured claim in Republic's bankruptcy case. Republic does business as Republic Airways.


•	ManaAir, LLC ("ManaAir"). In a series of transactions completed in January 2019, United obtained a 49.9% minority ownership stake in ManaAir, LLC ("ManaAir") and ManaAir purchased 100% of the equity of ExpressJet Airlines, Inc.


•	Champlain Enterprises LLC ("Champlain"). United owns a 40% minority ownership stake in Champlain. Champlain does business as CommutAir.

Other Investments. United owns approximately 9% of the preferred shares of Fulcrum BioEnergy, Inc. ("Fulcrum"), a company that is developing a process for transforming municipal solid waste into transportation fuels, including jet fuel and diesel. United records its investment in Fulcrum 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, 2018, the carrying value of United's investment was $48 million.

- 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

Debt

12 Months Ended

Dec. 31, 2018

Debt Disclosure [Abstract]

Debt

DEBT



(In millions)	At December 31,
	2018			2017
Secured
Notes payable, fixed interest rates of 0.0% to 9.52% (weighted average rate of 4.18% as of December 31, 2018), payable through 2030	$	8,811		$	8,661
Notes payable, floating interest rates of the London interbank offered rate ("LIBOR") plus 1.05% to 1.75%, payable through 2030	2,051			1,880
Term loan, LIBOR plus 1.75%, or alternative rate based on certain market rates plus 0.75%, due 2024	1,474			1,489
Unsecured
6.375% Senior Notes due 2018 (a)	—			300
6% Senior Notes due 2020 (a)	300			300
4.25% Senior Notes due 2022 (a)	400			400
5% Senior Notes due 2024 (a)	300			300
Other	300			101
	13,636			13,431
Less: unamortized debt discount, premiums and debt issuance costs	(191		)	(163		)
Less: current portion of long-term debt	(1,230		)	(1,565		)
Long-term debt, net	$	12,215		$	11,703

(a) UAL is the issuer of this debt. United is a guarantor.

The table below presents the Company's contractual principal payments (not including debt discount or debt issuance costs) at December 31, 2018 under then-outstanding long-term debt agreements in each of the next five calendar years (in millions):



2019	$	1,230
2020	1,310
2021	1,300
2022	1,653
2023	703
After 2023	7,440
	$	13,636

Secured debt

Credit and Guaranty Agreement. On March 29, 2017, United and UAL, as borrower and guarantor, respectively, entered into an Amended and Restated Credit and Guaranty Agreement (as amended, the "Credit Agreement"). The Credit Agreement consists of a $1.5 billion term loan due April 1, 2024 and a $2.0 billion revolving credit facility available for drawing until April 1, 2022. The obligations of United under the amended Credit Agreement are secured by liens on certain international route authorities, certain take-off and landing rights and related assets of United.

Term loan borrowings under the Credit Agreement bear interest at a variable rate equal to LIBOR plus a margin of 1.75% per annum, or another rate based on certain market interest rates, plus a margin of 0.75% per annum. The principal amount of the term loan must be repaid in consecutive quarterly installments of 0.25% of the original principal amount thereof, commencing on June 30, 2017, with any unpaid balance due on April 1, 2024. United may prepay all or a portion of the loan from time to time, at par plus accrued and unpaid interest.

As of December 31, 2018, United had its entire capacity of $2.0 billion available under the revolving credit facility of the Company's Credit Agreement. United pays a commitment fee equal to 0.75% per annum on the undrawn amount available under the revolving credit facility. If drawn, revolving loans under the Credit Agreement bear interest at a variable rate equal to LIBOR plus a margin of 2.25% per annum, or another rate based on certain market interest rates, plus a margin of 1.25% per annum.

As of December 31, 2018, United had cash collateralized $73 million of letters of credit, which generally have evergreen clauses and are expected to be renewed on an annual basis. As of December 31, 2018, United also had $418 million of surety bonds securing various obligations with expiration dates through 2022.

EETCs. As of December 31, 2018, United had $8.8 billion principal amount of equipment notes outstanding issued under EETC financings included in notes payable in the table of outstanding debt above. Generally, the structure of these EETC financings consists of pass-through trusts created by United to issue pass-through certificates, which represent fractional undivided interests in the respective pass-through trusts and are not obligations of United. The proceeds of the issuance of the pass-through certificates are used to purchase equipment notes which are issued by United and secured by its aircraft. The payment obligations under the equipment notes are those of United. Proceeds received from the sale of pass-through certificates are initially held by a depositary in escrow for the benefit of the certificate holders until United issues equipment notes to the trust, which purchases such notes with a portion of the escrowed funds. These escrowed funds are not guaranteed by United and are not reported as debt on United's consolidated balance sheet because the proceeds held by the depositary are not United's assets.

In February 2018, May 2018 and February 2019, United created separate EETC pass-through trusts, each of which issued pass-through certificates. The proceeds of the issuance of the pass-through certificates are used to purchase equipment notes issued by United and secured by its aircraft. The Company records the debt obligation upon issuance of the equipment notes rather than upon the initial issuance of the pass-through certificates. Certain details of the pass-through trusts with proceeds received from issuance of debt in 2018 are as follows (in millions, except stated interest rate):



EETC Date	Class	Principal		Final expected distribution date	Stated interest rate		Total debt recorded as of December 31, 2018		Proceeds received from issuance of debt during 2018		Remaining proceeds from issuance of debt to be received in future periods
February 2019	AA	$	717	August 2031	4.15	%	$	—	$	—	$	717
February 2019	A	296		August 2031	4.55	%	—		—		296
May 2018	B	226		March 2026	4.60	%	226		226		—
February 2018	AA	677		March 2030	3.50	%	677		677		—
February 2018	A	258		March 2030	3.70	%	258		258		—
		$	2,174				$	1,161	$	1,161	$	1,013

In 2018, United borrowed approximately $424 million aggregate principal amount from various financial institutions to finance the purchase of several aircraft delivered in 2018. The notes evidencing these borrowings, which are secured by the related aircraft, mature in 2030 and have interest rates comprised of LIBOR plus a specified margin.

Unsecured debt

4.25% Senior Notes due 2022. In September 2017, UAL issued $400 million aggregate principal amount of 4.25% Senior Notes due October 1, 2022 (the "4.25% Senior Notes due 2022"). These notes are fully and unconditionally guaranteed and recorded by United on its balance sheet as debt. The indenture for the 4.25% Senior Notes due 2022 requires UAL to offer to repurchase the notes for cash if certain changes of control of UAL occur at a purchase price equal to 101% of the principal amount of notes repurchased plus accrued and unpaid interest.

5% Senior Notes due 2024. In January 2017, UAL issued $300 million aggregate principal amount of 5% Senior Notes due February 1, 2024 (the "5% Senior Notes due 2024"). These notes are fully and unconditionally guaranteed and recorded by United on its balance sheet as debt. The indenture for the 5% Senior Notes due 2024 requires UAL to offer to repurchase the notes for cash if certain changes of control of UAL occur at a purchase price equal to 101% of the principal amount of notes repurchased plus accrued and unpaid interest.

As of December 31, 2018, UAL and United were in compliance with their respective 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
Various equipment notes and other notes payable	Secured by certain aircraft. The indentures contain events of default that are customary for aircraft financing, including in certain cases cross default to other related aircraft.
Credit Agreement	Secured by certain of United's international route authorities, specified take-off and landing slots at certain airports and certain other assets. The Credit Agreement requires 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 obligations under the Credit Agreement of 1.6 to 1.0 at all times. The Credit Agreement contains covenants that, among other things, restrict the ability of UAL and its restricted subsidiaries (as defined in the Credit Agreement) to incur additional indebtedness and to pay dividends on or repurchase stock, although, as of December 31, 2018, the Company had ample ability under these restrictions to repurchase stock under the Company's share repurchase program. The Credit Agreement contains events of default customary for this type of financing, including a cross default and cross acceleration provision to certain other material indebtedness of the Company.
6% Senior Notes due 2020 4.25% Senior Notes due 2022 5% Senior Notes due 2024	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 pay dividends on or repurchase stock, although the Company currently has ample ability under these restrictions to repurchase stock under the Company's share repurchase program.

Leases and Capacity Purchase Agreements

12 Months Ended

Dec. 31, 2018

Leases [Abstract]

Leases and Capacity Purchase Agreements

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.

In 2018, United entered into a new Airline Use and Lease Agreement at Chicago O'Hare International Airport ("Chicago O'Hare") with the City of Chicago with a lease term of approximately 15 years, effective May 12, 2018 through December 31, 2033. United also entered into several new ground and facility leases at Chicago O'Hare, effective May 12, 2018, for hangars, a ground equipment maintenance building, and employee parking with lease terms ranging from 15 years to 30 years.

At December 31, 2018, United's scheduled future minimum lease payments under operating leases having initial or remaining noncancelable lease terms of more than one year, aircraft leases, including aircraft rent under CPAs and capital leases (substantially all of which are for aircraft) were as follows (in millions):



	Capital Leases (b)			Facility and Other Operating Leases		Aircraft Operating Leases
2019	$	308		$	1,330	$	845
2020	170			1,351		682
2021	147			1,107		583
2022	123			970		407
2023	104			953		379
After 2023	1,268			7,029		1,160
Minimum lease payments (a)	$	2,120		$	12,740	$	4,056
Imputed interest	(837		)
Present value of minimum lease payments	1,283
Current portion	(149		)
Long-term obligations under capital leases	$	1,134

(a) Includes fair value lease and deferred financing fee balances, which are being amortized over the terms of their respective leases.

(b) Includes airport construction projects managed by United in which United has construction risk, including project cost overruns. The Company recorded an asset for project costs and a related liability equal to project costs funded by parties other than United. As of December 31, 2018, United had an asset balance of $886 million recorded in operating property and equipment and $920 million recorded in current and long-term obligations under capital leases for these airport construction projects.

As of December 31, 2018, United's aircraft capital lease minimum payments relate to leases of 28 mainline and 90 regional aircraft as well as to leases of nonaircraft assets. Imputed interest rate ranges are 3.5% to 115.1%.

Aircraft operating leases have initial terms of five to 26 years, with expiration dates ranging from 2019 through 2029. Under the terms of most 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 fair market value or a percentage of cost.

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 $1.3 billion of underlying debt and interest thereon as of December 31, 2018. These leases are typically with municipalities or other governmental entities, which are excluded from the consolidation requirements concerning a variable interest entity ("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. United has facility operating leases that extend to 2055.

United's nonaircraft rent expense was approximately $1.3 billion, $1.3 billion and $1.2 billion for the years ended December 31, 2018, 2017 and 2016, respectively.

In addition to nonaircraft rent and aircraft rent, which is separately presented in the consolidated statements of operations, United had aircraft rent related to regional aircraft operating leases, which is included as part of Regional capacity purchase expense in United's consolidated statement of operations, of $505 million, $458 million and $439 million for the years ended December 31, 2018, 2017 and 2016, respectively.

In connection with UAL Corporation's and United Air Lines, Inc.'s (predecessors to UAL and United) fresh-start reporting requirements upon their exit from Chapter 11 bankruptcy protection in 2006 and the Company's acquisition accounting adjustments related to the Company's merger transaction in 2010, lease valuation adjustments for operating leases were initially recorded in the consolidated balance sheet, representing the net present value of the differences between contractual lease rates and the fair market lease rates for similar leased assets at the time. An asset (liability) results when the contractual lease rates are more (less) favorable than market lease terms at the valuation date. The lease valuation adjustment is amortized on a straight-line basis as an increase (decrease) to rent expense over the individual applicable remaining lease terms, resulting in recognition of rent expense as if United had entered into the leases at market rates. The related remaining lease terms, primarily related to aircraft which make up the majority of the fair value lease adjustment balance, are one to six years for United. The lease valuation adjustments are classified within other noncurrent liabilities and the net accretion amounts are $60 million, $79 million and $82 million for the years ended December 31, 2018, 2017 and 2016, respectively.

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 reimbursement (incentive payment for operational performance) based on agreed performance metrics, subject to annual adjustments. The fees for carrier costs are based on specific rates for various operating expenses of the regional carriers, such as crew expenses, maintenance and aircraft ownership, some of which are multiplied by specific operating statistics (e.g., block hours, departures), while others are fixed monthly amounts. Under these CPAs, the Company is 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, and, in some cases, the Company owns or leases some or all of the aircraft subject to the CPA, and leases or subleases, as applicable, such aircraft to the regional carrier. United's CPAs are for 559 regional aircraft as of December 31, 2018, and the CPAs have terms expiring through 2029. Aircraft operated under CPAs include aircraft leased directly from the regional carriers and those owned by United or leased from third-party lessors and operated by the regional carriers. See Part I, Item 2, Properties, of this report for additional information.

In 2017, United entered into a five-year CPA with Air Wisconsin Airlines for regional service under the United Express brand to operate up to 65 CRJ200 aircraft. In addition, United extended the term of its existing CPA with ExpressJet Airlines to operate up to approximately 125 aircraft through December 31, 2022.

United recorded approximately $979 million, $907 million and $935 million in expenses related to its CPAs with its regional carriers, in which United is a minority shareholder, for the years ended December 31, 2018, 2017 and 2016, respectively. There were approximately $53 million and $24 million in accounts payable due to these companies as of December 31, 2018 and December 31, 2017, respectively. There were no material accounts receivables due from these companies as of December 31, 2018 and December 31, 2017. The CPAs with these related parties were executed in the ordinary course of business.

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. 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 aircraft and nonaircraft operating leases. 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 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, 2018, our future payments through the end of the terms of our CPAs are presented in the table below (in billions):



2019	$	2.2
2020	2.0
2021	1.8
2022	1.4
2023	0.8
After 2023	3.1
	$	11.3

The actual amounts we pay to our regional operators under CPAs could differ materially from these estimates. For example, a 10% increase or decrease in scheduled block hours for all of United's regional operators (whether as a result of changes in average daily utilization or otherwise) in 2019 would result in a corresponding change in annual cash obligations under the CPAs of approximately $160 million.

Variable Interest Entities

12 Months Ended

Dec. 31, 2018

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Variable Interest Entities

VARIABLE INTEREST ENTITIES

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.

Aircraft Leases. We are the lessee in a number of operating leases covering the majority of our leased aircraft. The lessors are trusts established specifically to purchase, finance and lease aircraft to us. These leasing entities meet the criteria for VIEs. We are generally not the primary beneficiary of the leasing entities if the lease terms are consistent with market terms at the inception of the lease and do not include a residual value guarantee, fixed-price purchase option or similar feature that obligates us to absorb decreases in value or entitles us to participate in increases in the value of the aircraft. This is the case for many of our operating leases; however, leases of 23 mainline jet aircraft contain a fixed-price purchase option that allow United to purchase the aircraft at predetermined prices on specified dates during the lease term. Additionally, leases covering 90 leased regional jet aircraft contain an option to purchase the aircraft at the end of the lease term at prices that, depending on market conditions, could be below fair value. United has not consolidated the related trusts because, even taking into consideration these purchase options, United is still not the primary beneficiary. United's maximum exposure under these leases is the remaining lease payments, which are reflected in future lease commitments in Note 11 of this report.

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 did 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.

Synergy affiliates.

•

BRW Aviation LLC ("BRW"): Synergy's wholly-owned affiliate, BRW, is a special purpose entity created to be the borrower of the Synergy Term Loan. BRW is also the owner of the collateral that secures the Synergy Term Loan, including Synergy's shares of AVH. BRW is a VIE and United holds variable interests in BRW including the Synergy Term Loan. However, United is not the primary beneficiary of BRW because it does not hold BRW equity and does not have management rights at BRW and therefore does not have the power to direct the activities that most significantly impact BRW's economic performance.


•	AVH: United concluded that AVH is a VIE and that United holds a variable interest through its call option on Synergy's AVH shares. However, United is not the primary beneficiary because it does not hold a material number of shares of AVH and does not have the power through any other agreements to direct the activities that most significantly impact AVH's economic performance.

Commitments and Contingencies

12 Months Ended

Dec. 31, 2018

Commitments and Contingencies Disclosure [Abstract]

COMMITMENTS AND CONTINGENCIES

NOTE 13 - COMMITMENTS AND CONTINGENCIES

Commitments. As of December 31, 2018, United had firm commitments and options to purchase aircraft from The Boeing Company ("Boeing"), Airbus S.A.S. ("Airbus") and Embraer S.A. ("Embraer") presented in the table below:



Aircraft Type		Number of Firm Commitments (a)
Airbus A350		45
Boeing 737 MAX		175
Boeing 777-300ER		4
Boeing 787		24
Embraer E175		25
(a) United also has options and purchase rights for additional aircraft.

The aircraft listed in the table above are scheduled for delivery from 2019 through 2027. To the extent the Company and the aircraft manufacturers with whom the Company has existing orders for new aircraft agree to modify the contracts governing those orders, the amount and timing of the Company's future capital commitments could change. In 2019, United expects to take delivery of 25 Embraer E175 aircraft, 20 Boeing 737 MAX aircraft, 8 Boeing 787 aircraft and 2 Boeing 777-300ER aircraft. United also has agreements to purchase 20 used Airbus A319 aircraft with expected delivery dates through 2022.

During the third quarter of 2018, United entered into an agreement with the lessor of 54 Embraer ERJ 145 aircraft to purchase those aircraft in 2019. The provisions of such agreement resulted in a change in accounting classification of the applicable leases from operating leases to capital leases up until the applicable purchase date.

The table below summarizes United's commitments as of December 31, 2018, which primarily relate to the acquisition of aircraft and related spare engines, aircraft improvements and include other capital purchase commitments for the years ended December 31 (in billions). Any new firm aircraft orders, including through the exercise of purchase options and purchase rights, will increase the total future capital commitments of the Company.



2019	$	4.2
2020	5.3
2021	3.5
2022	2.8
2023	1.9
After 2023	7.0
	$	24.7

In February 2019, the Company secured $1.0 billion of EETC financing to finance certain aircraft deliveries in 2018 and 2019. The Company has also secured backstop financing commitments from certain of its aircraft manufacturers for a limited number of its future aircraft deliveries, subject to certain customary conditions. Financing may be necessary to satisfy the Company's capital commitments for its firm order aircraft and other related capital expenditures.

Legal and Environmental. The Company has certain contingencies resulting from litigation and claims incident to the ordinary course of business. As of December 31, 2018, 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 the ultimate disposition of the litigation and claims will not materially affect the Company's consolidated financial position or results of operations. The Company records liabilities for legal and environmental claims when a loss is probable and reasonably estimable. These amounts are recorded based on the Company's assessments of the likelihood of their eventual disposition.

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 tort liabilities that arise out of the use, occupancy, 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 tort liabilities and related indemnities are covered by insurance (subject to deductibles). Additionally, certain leased premises such as fueling stations or storage facilities include indemnities of such parties for any environmental liability that may arise out of or relate to the use of the leased premises.

As of December 31, 2018, 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 approximately $1.3 billion of these obligations are accounted for as operating leases with the associated expense recorded on a straight-line basis resulting in ratable accrual of the lease obligation over the expected lease term. These tax-exempt special facilities revenue bonds are included in our lease commitments disclosed in Note 11 of this report. The leasing arrangements associated with approximately $466 million of these obligations are accounted for as capital leases. All of these bonds are due between 2019 and 2038.

In connection with funding the Synergy Loan Agreement, the Company entered into an agreement with AVH's significant minority shareholder, Kingsland Holdings Limited ("Kingsland"), pursuant to which, in return for Kingsland's pledge of its 144.8 million shares of AVH common stock (equivalent to 18.1 million American Depositary Receipts ("ADRs")) and its consent to Synergy's pledge of its AVH common stock to United under the Synergy Loan Agreement, United (1) granted to Kingsland the right to put its shares of AVH common stock to United at market price on the fifth anniversary of the Synergy Loan Agreement, and (2) guaranteed Synergy's obligation to pay Kingsland (which amount, if paid by United, will increase United's secured loan to Synergy by such amount) if the market price of AVH common stock on the fifth anniversary is less than $12 per ADR on the NYSE, for an aggregate maximum possible combined put payment and guarantee amount on the fifth anniversary of $217.2 million. Accordingly, the Company recorded a liability of $31 million for the fair value of its guarantee to loan additional funds to Synergy if required. Any additional loans to Synergy would be collateralized by Synergy's shares of AVH stock and other collateral.

Increased Cost Provisions. In United's financing transactions that include loans, 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 in which the interest rate is based on LIBOR, 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. At December 31, 2018, the Company had $3.5 billion of floating rate debt and $27 million of fixed rate debt, with remaining terms of up to 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 12 years and an aggregate balance of $3.2 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.

As of December 31, 2018, United is the guarantor of $145 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 above for the Company's debt, and the Company would potentially be responsible for those costs under the guarantees.

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 tax-exempt bonds, either special facilities lease revenue bonds or general airport revenue bonds, issued by various local municipalities. 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 the bonds. As of December 31, 2018, approximately $1.7 billion principal amount of such bonds were 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, 2018, the Company's contingent exposure was approximately $164 million principal amount of such bonds 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 the tax-exempt bonds are paid in full, which ranges from 2022 to 2051. The Company did not record a liability at the time these indirect guarantees were made.

Regional Capacity Purchase. As of December 31, 2018, United had 292 call options to purchase regional jet aircraft being operated by certain of its regional carriers with contract dates extending until 2029. These call options are exercisable upon wrongful termination or breach of contract, among other conditions. None of the call options were exercisable at December 31, 2018.

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, 2018, United, including its subsidiaries, had approximately 92,000 employees. Approximately 83% of United's employees were represented by various U.S. labor organizations as of December 31, 2018. The agreement with the International Brotherhood of Teamsters (the "IBT") contains provisions that require the Company to align contract terms with other airlines' workgroups under certain conditions.

On October 23, 2018, United's Catering Operations employees voted to unionize under the Railway Labor Act. In an election overseen by the National Mediation Board, UNITE HERE received the majority of the votes and was officially certified to represent United's frontline Catering Operations employees. The Company expects contract negotiations to begin in 2019.

Special Charges

12 Months Ended

Dec. 31, 2018

Business Combinations [Abstract]

SPECIAL CHARGES

Special charges in the statements of consolidated operations consisted of the following for the years ended December 31 (in millions):



Operating:	2018			2017 (a)			2016 (a)
Impairment of assets	$	377		$	25		$	412
Termination of an engine maintenance service agreement	64			—			—
Severance and benefit costs	41			116			37
Cleveland airport lease restructuring	—			—			74
Labor agreement costs	—			—			171
(Gains) losses on sale of assets and other special charges	5			35			51
Total operating special charges	487			176			745
Nonoperating:
Postretirement curtailment gain	—			—			(107		)
Gains on extinguishment of debt and other	—			—			(1		)
Total operating and nonoperating special charges before income taxes	487			176			637
Nonoperating mark-to-market ("MTM") losses on financial instruments	5			—			—
Total special charges and MTM losses on financial instruments	492			176			637
Income tax benefit	(110		)	(63		)	(229		)
Income tax adjustments (Note 7)	(5		)	(179		)	180
Total special charges and MTM losses on financial instruments, net of income taxes and income tax adjustments	$	377		$	(66	)	$	588

(a) Amounts adjusted due to the adoption of Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606) and Accounting Standards Update No. 2017-07, Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost. See Note 1 to the financial statements contained in Part II, Item 8 of this report for additional information.

2018

The Company conducted its annual impairment review of intangible assets in the fourth quarter of 2018, which consisted of a comparison of the book value of specific assets to the fair value of those assets. Due to increased costs without sufficient corresponding increases in revenue in the Hong Kong market, the Company determined that the value of its Hong Kong routes had been impaired. Accordingly, in the fourth quarter of 2018, the Company recorded a special non-cash impairment charge of $206 million ($160 million net of taxes) associated with its Hong Kong routes. The collateral pledged under the Company's term loan, including the Hong Kong routes, continues to be sufficient to satisfy the loan covenants. The Company determined the fair value of the Hong Kong routes using a variation of the income approach known as the excess earnings method, which discounts an asset's projected future net cash flows to determine the current fair value. Assumptions used in the discounted cash flow methodology include a discount rate, which is based upon the Company's current weighted average cost of capital plus an asset-specific risk factor, and a projection of sales, expenses, gross margin, tax rates and contributory asset charges for four future years and a terminal growth rate. The assumptions used for future projections are determined based upon the Company's asset-specific forecasts along with the Company's strategic plan. These assumptions are inherently uncertain as they relate to future events and circumstances. Actual results will be influenced by the competitive environment, fuel costs and other expenses, and potentially other unforeseen events or circumstances that could have a material negative impact on future results.

In May 2018, the Brazil–United States open skies agreement was ratified, which provides air carriers with unrestricted access between the United States and Brazil. The Company determined that the approval of the open skies agreement impaired the entire value of its Brazil route authorities because the agreement removes all limitations or reciprocity requirements for flights between the United States and Brazil. Accordingly, the Company recorded a $105 million special charge ($82 million net of taxes) to write off the entire value of the intangible asset associated with its Brazil routes. This asset is not part of any collateral pledged against any of the Company's borrowings. The Company continues to maintain its slot assets related to Brazil since airport access is still regulated by slot allocations that are limited by airport facility constraints.

During 2018, the Company also recorded $66 million ($51 million net of taxes) of fair value adjustments related to aircraft purchased off lease, write-offs of unexercised aircraft purchase options and other impairments related to certain fleet types and international slots no longer in use.

During 2018, the Company recorded a one-time termination charge of $64 million ($50 million net of tax) related to one of its engine maintenance service agreements.

During 2018, the Company recorded severance and benefit costs related to a voluntary early-out program for its technicians and related employees represented by the IBT of $22 million ($17 million net of taxes). In the first quarter of 2017, approximately 1,000 technicians and related employees elected to voluntarily separate from the Company and receive a severance payment, with a maximum value of $100,000 per participant, based on years of service, with retirement dates through the end of 2018. Also during 2018, the Company recorded other management severance of $19 million ($15 million net of taxes).

During 2018, the Company recorded gains of $28 million ($22 million net of taxes) for the change in market value of certain of its equity investments. Also, the Company recorded losses of $33 million ($26 million net of taxes) for the change in fair value of certain derivative assets related to equity of Avianca Holdings S.A. For equity investments and derivative assets subject to MTM accounting, the Company records gains and losses as part of Nonoperating income (expense): Miscellaneous, net in its statements of consolidated operations.

2017

During 2017 the Company recorded a $10 million ($6 million net of taxes) impairment charge related to obsolete spare parts inventory and a $15 million ($10 million net of taxes) intangible asset impairment charge related to a maintenance service agreement.

During 2017, the Company recorded $83 million ($53 million net of taxes) of severance and benefit costs related to the voluntary early-out program for its technicians and related employees represented by the IBT as described above. Also during 2017, the Company recorded $33 million ($21 million net of taxes) of other management severance.

2016

In April 2016, the Federal Aviation Administration ("FAA") announced that it will designate Newark Liberty International Airport ("Newark") as a Level 2 schedule-facilitated airport under the International Air Transport Association Worldwide Slot Guidelines. The designation was associated with an updated demand and capacity analysis of Newark by the FAA. In 2016, the Company determined that the FAA's action impaired the entire value of its Newark slots because the slots are no longer the mechanism that governs take-off and landing rights. Accordingly, the Company recorded a $412 million special charge ($264 million net of taxes) to write off the intangible asset.

During 2016, the Company recorded $37 million ($24 million net of taxes) of severance and benefit costs related to a voluntary early-out program for the Company's flight attendants and other severance agreements. In 2014, more than 2,500 flight attendants elected to voluntarily separate from the Company for a severance payment, with a maximum value of $100,000 per participant, based on years of service, with retirement dates through the end of 2016.

In 2016, the City of Cleveland agreed to amend the Company's lease, which runs through 2029, associated with certain excess airport terminal space (principally Terminal D) and related facilities at Hopkins International Airport ("Cleveland"). The Company recorded an accrual for remaining payments under the lease for facilities that the Company no longer uses and will continue to incur costs under the lease without economic benefit to the Company. This liability was measured and recorded at its fair value when the Company ceased its right to use such facilities leased to it pursuant to the lease. The Company recorded a net charge of $74 million ($47 million net of taxes) related to the amended lease.

The fleet service, passenger service, storekeeper and other employees represented by the International Association of Machinists and Aerospace Workers (the "IAM") ratified seven new contracts with the Company which extended the contracts through 2021. The technicians and related employees represented by the IBT ratified a six-year joint collective bargaining agreement which extended the contract through 2022. During 2016, the Company recorded $171 million ($110 million net of taxes) of special charges primarily for payments in conjunction with the IAM and IBT agreements described above.

As part of the ratified contract with the IBT, the Company amended some of its technicians and related employees' postretirement medical plans. The amendments triggered curtailment accounting, resulting in the recognition of a one-time $60 million gain ($38 million net of taxes) for accelerated recognition of a prior service credit in one of the plans. Also, as part of the ratified contract with the Association of Flight Attendants, the Company amended two of its flight attendant postretirement medical plans. The amendments triggered curtailment accounting, resulting in the recognition of a one-time $47 million gain ($30 million net of taxes) for accelerated recognition of a prior service credit.

Accrual Activity

Activity related to the accruals for severance and medical costs and future lease payments on permanently grounded aircraft is as follows (in millions):



	Severance/ Benefit Costs			Permanently Grounded Aircraft
Balance at December 31, 2015	$	27		$	78
Accrual and related adjustments	37			(17		)
Payments	(50		)	(20		)
Balance at December 31, 2016	14			41
Accrual	116			(4		)
Payments	(93		)	(15		)
Balance at December 31, 2017	37			22
Accrual	41			(7		)
Payments	(53		)	(3		)
Balance at December 31, 2018	$	25		$	12

Selected Quarterly Financial Data (Unaudited)

12 Months Ended

Dec. 31, 2018

Quarterly Financial Information Disclosure [Abstract]

Selected Quarterly Financial Data (Unaudited)

NOTE 15 - SELECTED QUARTERLY FINANCIAL DATA (UNAUDITED)



UAL	Quarter Ended
(In millions, except per share amounts)	March 31		June 30		September 30		December 31
2018
Operating revenue	$	9,032	$	10,777	$	11,003	$	10,491
Income from operations	276		1,161		1,203		652
Net income	147		684		836		462
Basic earnings per share	0.52		2.49		3.07		1.71
Diluted earnings per share	0.52		2.48		3.06		1.70

2017 (a)
Operating revenue	$	8,426	$	10,008	$	9,899	$	9,451
Income from operations	320		1,437		1,138		776
Net income	99		821		645		579
Basic earnings per share	0.32		2.67		2.15		1.99
Diluted earnings per share	0.32		2.67		2.15		1.98

UAL's quarterly financial data is subject to seasonal fluctuations and historically its second and third quarter financial results, which reflect higher travel demand, are better than its first and fourth quarter financial results. UAL's quarterly results were impacted by the following significant items (in millions):



	Quarter Ended
	March 31			June 30			September 30			December 31
2018
Operating:
Impairment of assets	$	23		$	111		$	11		$	232
Termination of an engine maintenance service agreement	—			—			—			64
Severance and benefit costs	14			11			9			7
(Gains) losses on sale of assets and other special charges	3			7			(3		)	(2		)
Total operating special charges	40			129			17			301
Nonoperating:
Nonoperating mark-to-market ("MTM") (gains) losses on financial instruments	(45		)	135			(29		)	(56		)
Total special charges and MTM (gains) losses on financial instruments	(5		)	264			(12		)	245
Income taxes:
Income tax expense (benefit) related to special charges and MTM gains and losses on financial instruments	1			(59		)	3			(55		)
Income tax adjustments	—			—			—			(5		)
Total special charges and MTM (gains) losses on financial instruments, net of tax	$	(4	)	$	205		$	(9	)	$	185

2017 (a)
Operating:
Severance and benefit costs	$	37		$	41		$	23		$	15
Impairment of assets	—			—			15			10
(Gains) losses on sale of assets and other special charges	14			3			12			6
Total operating special charges	51			44			50			31
Income taxes:
Income tax benefit related to special charges	(18		)	(16		)	(18		)	(11		)
Income tax adjustments	—			—			—			(179		)
Total operating special charges, net of income taxes and income tax adjustments	$	33		$	28		$	32		$	(159	)

See Note 14 of this report for additional information related to these items.

Schedule II - Valuation and Qualifying Accounts

12 Months Ended

Dec. 31, 2018

Valuation and Qualifying Accounts [Abstract]

Schedule II - Valuation and Qualifying Accounts

Schedule II

Valuation and Qualifying Accounts

For the Years Ended December 31, 2018, 2017 and 2016



(In millions) Description	Balance at Beginning of Period		Additions Charged to Costs and Expenses		Deductions (a)		Other		Balance at End of Period
Allowance for doubtful accounts:
2018	$	7	$	17	$	16	$	—	$	8
2017	10		20		23		—		7
2016	18		18		26		—		10
Obsolescence allowance—spare parts:
2018	$	354	$	73	$	15	$	—	$	412
2017	295		75		17		1		354
2016	235		61		16		15		295
Valuation allowance for deferred tax assets:
2018	$	63	$	2	$	6	$	—	$	59
2017	68		11		27		11		63
2016	48		47		27		—		68

(a) Deduction from reserve for purpose for which reserve was created.

Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2018

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— The Company presents Passenger revenue, Cargo revenue and Other operating revenue on its income statement. 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.


	Revenue by Geography. The Company further disaggregates revenue by geographic regions. 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.

Frequent Flyer Accounting

•


•	Marketing – United has a performance obligation to provide Chase access to its customer list and the use of its 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.

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.

Short-term Investments

Accounts Receivable

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

Maintenance and Repairs

Lease Fair Value Adjustments

Lease Fair Value Adjustments—Lease fair value adjustments, which arose from recording operating leases at fair value under fresh start or business combination accounting, are amortized on a straight-line basis over the related lease term.

Regional Capacity Purchase

Regional Capacity Purchase—Payments made to regional carriers under capacity purchase agreements ("CPAs") are reported in Regional capacity purchase in our consolidated statements of operations.

Advertising

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

Intangibles

Long-Lived Asset Impairments

Share-Based Compensation

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.

Retirement of Leased Aircraft

Uncertain Income Tax Positions

Labor Costs

Third-Party Business

Recently Issued Accounting Standards



Statements of Consolidated Operations for the Years Ended December 31,
	As Previously Reported						New Revenue Standard Adjustments						New Retirement Standard Adjustments						As Adjusted
	2017			2016			2017			2016			2017			2016			2017			2016
Operating revenue:
Passenger revenue	$	32,404		$	31,457		$	2,056		$	1,972		$	—		$	—		$	34,460		$	33,429
Cargo	1,035			876			79			58			—			—			1,114			934
Other operating revenue	4,297			4,223			(2,087		)	(2,028		)	—			—			2,210			2,195
Total operating revenue	37,736			36,556			48			2			—			—			37,784			36,558
Operating expenses	34,238			32,218			(21		)	(12		)	(104		)	8			34,113			32,214
Operating income	3,498			4,338			69			14			104			(8		)	3,671			4,344
Nonoperating expense, net	(499		)	(519		)	(28		)	(60		)	(104		)	8			(631		)	(571		)
Income before income taxes	2,999			3,819			41			(46		)	—			—			3,040			3,773
Income tax expense	868			1,556			28			(17		)	—			—			896			1,539
Net income	$	2,131		$	2,263		$	13		$	(29	)	$	—		$	—		$	2,144		$	2,234

Earnings per share, basic	$	7.04		$	6.86		$	0.04		$	(0.09	)	$	—		$	—		$	7.08		$	6.77
Earnings per share, diluted	$	7.02		$	6.85		$	0.04		$	(0.09	)	$	—		$	—		$	7.06		$	6.76



Consolidated Balance Sheet as of December 31, 2017
	As Previously Reported		New Revenue Standard Adjustments			As Adjusted
Current assets:
Prepaid expenses and other	$	1,051	$	20		$	1,071
Current liabilities:
Advance ticket sales	3,876		64			3,940
Frequent flyer deferred revenue	2,176		16			2,192
Other	569		7			576
Other liabilities and deferred credits:
Frequent flyer deferred revenue	2,565		26			2,591
Deferred income taxes	225		(21		)	204
Stockholders' equity:
Retained earnings	$	4,621	$	(72	)	$	4,549

The adoption of the New Lease Standard is expected to impact our reported results as shown in the tables below (in millions, except per share amounts):



Consolidated Balance Sheets as of December 31,
	As Reported						New Lease Standard Adjustments						As Adjusted
	2018			2017			2018			2017			2018			2017
Current assets:
Receivables, less allowance for doubtful accounts	$	1,346		$	1,340		$	80		$	126		$	1,426		$	1,466
Prepaid expenses and other	913			1,071			(180		)	(208		)	733			863

Operating property and equipment:
Other property and equipment (owned)	7,919			6,946			(1,041		)	(922		)	6,878			6,024
Less-Accumulated depreciation and amortization (owned)	(12,760		)	(11,159		)	140			92			(12,620		)	(11,067		)
Flight equipment (finance leases) (a)	1,029			1,151			(37		)	(211		)	992			940
Less-Accumulated amortization	(654		)	(777		)	8			169			(646		)	(608		)

Operating lease assets
Flight equipment	—			—			2,380			3,102			2,380			3,102
Other property and equipment	—			—			2,882			2,975			2,882			2,975

Current liabilities:
Current maturities of finance leases (a)	149			128			(26		)	(50		)	123			78
Current maturities of operating leases	—			—			719			949			719			949
Other	619			576			(66		)	(58		)	553			518

Long-term obligations under finance leases (a)	1,134			996			(910		)	(766		)	224			230
Long-term obligations under operating leases	—			—			5,276			5,789			5,276			5,789

Other liabilities and deferred credits:
Deferred income taxes	814			204			14			16			828			220
Other	1,832			1,832			(822		)	(811		)	1,010			1,021

Stockholders' equity:
Retained earnings	6,668			4,549			47			54			6,715			4,603

(a) Finance leases, under the New Lease Standard, are the equivalent of capital leases under Topic 840.



Statements of Consolidated Operations for the Years Ended December 31,
	As Reported						New Lease Standard Adjustments						As Adjusted
	2018			2017			2018			2017			2018			2017
Operating expense:
Regional capacity purchase	$	2,601		$	2,232		$	48		$	36		$	2,649		$	2,268
Landing fees and other rent	2,359			2,240			90			70			2,449			2,310
Depreciation and amortization	2,240			2,149			(75		)	(53		)	2,165			2,096
Total operating expenses	38,011			34,113			63			53			38,074			34,166
Operating income	3,292			3,671			(63		)	(53		)	3,229			3,618

Nonoperating income (expense):
Interest expense	(729		)	(671		)	59			45			(670		)	(626		)
Interest capitalized	70			84			(5		)	(10		)	65			74
Total nonoperating expense, net	(634		)	(631		)	53			36			(581		)	(595		)
Income before income taxes	2,658			3,040			(10		)	(17		)	2,648			3,023
Income tax expense	529			896			(3		)	(16		)	526			880
Net income	$	2,129		$	2,144		$	(7	)	$	(1	)	$	2,122		$	2,143
Earnings per share, basic	$	7.73		$	7.08		$	(0.03	)	$	—		$	7.70		$	7.08
Earnings per share, diluted	$	7.70		$	7.06		$	(0.03	)	$	—		$	7.67		$	7.06

Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2018

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):



	2018		2017¹		2016¹
Domestic (U.S. and Canada)	$	25,552	$	23,114	$	22,151
Atlantic	7,103		6,340		6,194
Pacific	5,188		4,914		4,984
Latin America	3,460		3,416		3,229
Total	$	41,303	$	37,784	$	36,558

(1) Amounts adjusted due to the adoption of Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606). See (u) below for additional information.

Roll Forward of Frequent Flyer Deferred Revenue

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



	Twelve Months Ended December 31,
	2018			2017
Total Frequent flyer deferred revenue - beginning balance	$	4,783		$	4,889
Total miles awarded	2,451			2,077
Travel miles redeemed (Passenger revenue)	(2,068		)	(2,004		)
Non-travel miles redeemed (Other operating revenue)	(161		)	(179		)
Total Frequent flyer deferred revenue - ending balance	$	5,005		$	4,783

Impact of the Adoption of the New Revenue Standard and the New Retirement Standard and the Expected Impact of the Adoption of the New Lease Standard

The adoption of the New Lease Standard is expected to impact our reported results as shown in the tables below (in millions, except per share amounts):



Consolidated Balance Sheets as of December 31,
	As Reported						New Lease Standard Adjustments						As Adjusted
	2018			2017			2018			2017			2018			2017
Current assets:
Receivables, less allowance for doubtful accounts	$	1,346		$	1,340		$	80		$	126		$	1,426		$	1,466
Prepaid expenses and other	913			1,071			(180		)	(208		)	733			863

Operating property and equipment:
Other property and equipment (owned)	7,919			6,946			(1,041		)	(922		)	6,878			6,024
Less-Accumulated depreciation and amortization (owned)	(12,760		)	(11,159		)	140			92			(12,620		)	(11,067		)
Flight equipment (finance leases) (a)	1,029			1,151			(37		)	(211		)	992			940
Less-Accumulated amortization	(654		)	(777		)	8			169			(646		)	(608		)

Operating lease assets
Flight equipment	—			—			2,380			3,102			2,380			3,102
Other property and equipment	—			—			2,882			2,975			2,882			2,975

Current liabilities:
Current maturities of finance leases (a)	149			128			(26		)	(50		)	123			78
Current maturities of operating leases	—			—			719			949			719			949
Other	619			576			(66		)	(58		)	553			518

Long-term obligations under finance leases (a)	1,134			996			(910		)	(766		)	224			230
Long-term obligations under operating leases	—			—			5,276			5,789			5,276			5,789

Other liabilities and deferred credits:
Deferred income taxes	814			204			14			16			828			220
Other	1,832			1,832			(822		)	(811		)	1,010			1,021

Stockholders' equity:
Retained earnings	6,668			4,549			47			54			6,715			4,603

(a) Finance leases, under the New Lease Standard, are the equivalent of capital leases under Topic 840.

The tables below present the impact of the adoption of the New Revenue Standard and the New Retirement Standard on select accounts and captions of UAL's statements of consolidated operations for the twelve months ended December 31, 2017 and 2016 (in millions, except per share amounts) and the impact on UAL's balance sheet accounts and captions as of December 31, 2017 (in millions):



Statements of Consolidated Operations for the Years Ended December 31,
	As Previously Reported						New Revenue Standard Adjustments						New Retirement Standard Adjustments						As Adjusted
	2017			2016			2017			2016			2017			2016			2017			2016
Operating revenue:
Passenger revenue	$	32,404		$	31,457		$	2,056		$	1,972		$	—		$	—		$	34,460		$	33,429
Cargo	1,035			876			79			58			—			—			1,114			934
Other operating revenue	4,297			4,223			(2,087		)	(2,028		)	—			—			2,210			2,195
Total operating revenue	37,736			36,556			48			2			—			—			37,784			36,558
Operating expenses	34,238			32,218			(21		)	(12		)	(104		)	8			34,113			32,214
Operating income	3,498			4,338			69			14			104			(8		)	3,671			4,344
Nonoperating expense, net	(499		)	(519		)	(28		)	(60		)	(104		)	8			(631		)	(571		)
Income before income taxes	2,999			3,819			41			(46		)	—			—			3,040			3,773
Income tax expense	868			1,556			28			(17		)	—			—			896			1,539
Net income	$	2,131		$	2,263		$	13		$	(29	)	$	—		$	—		$	2,144		$	2,234

Earnings per share, basic	$	7.04		$	6.86		$	0.04		$	(0.09	)	$	—		$	—		$	7.08		$	6.77
Earnings per share, diluted	$	7.02		$	6.85		$	0.04		$	(0.09	)	$	—		$	—		$	7.06		$	6.76



Consolidated Balance Sheet as of December 31, 2017
	As Previously Reported		New Revenue Standard Adjustments			As Adjusted
Current assets:
Prepaid expenses and other	$	1,051	$	20		$	1,071
Current liabilities:
Advance ticket sales	3,876		64			3,940
Frequent flyer deferred revenue	2,176		16			2,192
Other	569		7			576
Other liabilities and deferred credits:
Frequent flyer deferred revenue	2,565		26			2,591
Deferred income taxes	225		(21		)	204
Stockholders' equity:
Retained earnings	$	4,621	$	(72	)	$	4,549



Statements of Consolidated Operations for the Years Ended December 31,
	As Reported						New Lease Standard Adjustments						As Adjusted
	2018			2017			2018			2017			2018			2017
Operating expense:
Regional capacity purchase	$	2,601		$	2,232		$	48		$	36		$	2,649		$	2,268
Landing fees and other rent	2,359			2,240			90			70			2,449			2,310
Depreciation and amortization	2,240			2,149			(75		)	(53		)	2,165			2,096
Total operating expenses	38,011			34,113			63			53			38,074			34,166
Operating income	3,292			3,671			(63		)	(53		)	3,229			3,618

Nonoperating income (expense):
Interest expense	(729		)	(671		)	59			45			(670		)	(626		)
Interest capitalized	70			84			(5		)	(10		)	65			74
Total nonoperating expense, net	(634		)	(631		)	53			36			(581		)	(595		)
Income before income taxes	2,658			3,040			(10		)	(17		)	2,648			3,023
Income tax expense	529			896			(3		)	(16		)	526			880
Net income	$	2,129		$	2,144		$	(7	)	$	(1	)	$	2,122		$	2,143
Earnings per share, basic	$	7.73		$	7.08		$	(0.03	)	$	—		$	7.70		$	7.08
Earnings per share, diluted	$	7.70		$	7.06		$	(0.03	)	$	—		$	7.67		$	7.06

Reconciliation of Cash, Cash Equivalents and Restricted Cash



	UAL						United
	At December 31,						At December 31,
	2018		2017		2016		2018		2017		2016
Current assets:
Cash and cash equivalents	$	1,694	$	1,482	$	2,179	$	1,688	$	1,476	$	2,173
Restricted cash included in Prepaid expenses and other	—		18		—		—		18		—
Other assets:
Restricted cash	105		91		124		105		91		124
Total cash, cash equivalents and restricted cash shown in the statement of consolidated cash flows	$	1,799	$	1,591	$	2,303	$	1,793	$	1,585	$	2,297

Reconciliation of Cash, Cash Equivalents and Restricted Cash



	UAL						United
	At December 31,						At December 31,
	2018		2017		2016		2018		2017		2016
Current assets:
Cash and cash equivalents	$	1,694	$	1,482	$	2,179	$	1,688	$	1,476	$	2,173
Restricted cash included in Prepaid expenses and other	—		18		—		—		18		—
Other assets:
Restricted cash	105		91		124		105		91		124
Total cash, cash equivalents and restricted cash shown in the statement of consolidated cash flows	$	1,799	$	1,591	$	2,303	$	1,793	$	1,585	$	2,297

Estimated Useful Lives of Property and Equipment

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



		Estimated Useful Life (in years)
Aircraft 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

Goodwill and Other Intangible Assets (Tables)

12 Months Ended

Dec. 31, 2018

Goodwill and Intangible Assets Disclosure [Abstract]

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):



	2018				2017
Item	Gross Carrying Amount		Accumulated Amortization		Gross Carrying Amount		Accumulated Amortization
Goodwill	$	4,523			$	4,523

Finite-lived intangible assets
Frequent flyer database	$	1,177	$	884	$	1,177	$	832
Hubs	145		97		145		89
Contracts	120		106		121		103
Patents and tradenames	108		108		108		108
Airport slots and gates	97		97		97		97
Other	109		88		109		84
Total	$	1,756	$	1,380	$	1,757	$	1,313
Indefinite-lived intangible assets
Route authorities	$	1,240			$	1,562
Airport slots and gates	546				536
Tradenames and logos	593				593
Alliances	404				404
Total	$	2,783			$	3,095

Earnings Per Share (Tables)

12 Months Ended

Dec. 31, 2018

Earnings Per Share [Abstract]

Computation of Earnings Per Share

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



	2018		2017 (a)		2016 (a)
Earnings available to common stockholders	$	2,129	$	2,144	$	2,234

Basic weighted-average shares outstanding	275.5		302.7		329.9
Effect of employee stock awards	1.2		0.9		0.4
Diluted weighted-average shares outstanding	276.7		303.6		330.3

Earnings per share, basic	$	7.73	$	7.08	$	6.77
Earnings per share, diluted	$	7.70	$	7.06	$	6.76

Share-Based Compensation Plans (Tables)

12 Months Ended

Dec. 31, 2018

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

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



	2018		2017		2016
Compensation cost:
RSUs	$	98	$	63	$	58
Restricted stock	2		8		11
Stock options	1		2		1
Total	$	101	$	73	$	70

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

Summary of RSU and Restricted Stock Activity

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



	Liability Awards		Equity Awards
	RSUs		RSUs		Weighted- Average Grant Price		Restricted Stock		Weighted- Average Grant Price
Outstanding at December 31, 2015	2.6		—		$	—	0.3		$	48.68
Granted	1.0		0.9		51.60		0.4		50.63
Vested	(1.4	)	—		—		(0.1	)	41.47
Forfeited	(0.1	)	(0.1	)	50.57		(0.1	)	53.42
Outstanding at December 31, 2016	2.1		0.8		51.67		0.5		52.00
Granted	0.6		1.0		71.68		—		—
Vested	(0.7	)	(0.3	)	51.81		(0.2	)	51.60
Forfeited	(0.2	)	(0.1	)	57.49		—		—
Outstanding at December 31, 2017	1.8		1.4		63.99		0.3		52.30
Granted	0.7		1.1		67.74		—		—
Vested	(0.5	)	(0.5	)	63.02		(0.2	)	53.24
Forfeited	(0.1	)	(0.2	)	67.34		—		—
Outstanding at December 31, 2018	1.9		1.8		66.29		0.1		51.17

Accumulated Other Comprehensive Income (Loss) (Tables)

12 Months Ended

Dec. 31, 2018

Equity [Abstract]

Components of AOCI

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



	Pension and Other Postretirement Liabilities				Fuel Derivatives Contracts			Investments and Other			Deferred Taxes				Total
Balance at December 31, 2015	$	(363	)		$	(215	)	$	3		$	(256	)		$	(831	)
Other comprehensive income (loss) before reclassifications	(517		)	(a)	(4		)	—			187				(334		)
Amounts reclassified from accumulated other comprehensive income	26				217			(2		)	95				336
Balance at December 31, 2016	(854		)		(2		)	1			26				(829		)
Other comprehensive income (loss) before reclassifications	(306		)	(a)	—			(7		)	74				(239		)
Amounts reclassified from accumulated other comprehensive income	58				2			—			(21		)		39
Reclassification of stranded tax effects	—				—			—			(118		)	(b)	(118		)
Balance at December 31, 2017	(1,102		)		—			(6		)	(39		)		(1,147		)
Other comprehensive income (loss) before reclassifications	377			(a)	—			(5		)	(83		)		289
Amounts reclassified from accumulated other comprehensive income	62				—			—			(13		)		49
Amounts reclassified to retained earnings	—				—			7			(1		)		6
Balance at December 31, 2018	$	(663	)		$	—		$	(4	)	$	(136	)		$	(803	)



Details about AOCI Components	Amount Reclassified from AOCI to Income							Affected Line Item in the Statement Where Net Income is Presented
	Year Ended December 31,
	2018		2017		2016
Fuel derivative contracts
Fuel contracts-reclassifications of losses into earnings	$	—	$	2	$	217		Aircraft fuel
Pension and Postretirement liabilities and other
Amortization of unrecognized (gains) losses and prior service cost (c)	62		58		26			Miscellaneous, net
Investments and other
Available-for-sale securities - reclassifications of gains into earnings	—		—		(2		)	Miscellaneous, net

(b) This amount represents the reclassification from AOCI to RE of the stranded tax effects resulting from the enactment of the Tax Cuts and Jobs Act (the "Tax Act").

(c) This AOCI component is included in the computation of net periodic pension and other postretirement costs (see Note 8 of this report for additional information).

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2018

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, as follows (in millions):



UAL	2018			2017 (a)			2016 (a)
Income tax provision at statutory rate	$	558		$	1,064		$	1,320
State income taxes, net of federal income tax benefit	29			30			38
Foreign tax rate differential	(84		)	(43		)	—
Global intangible low-taxed income	4			—			—
Foreign income taxes	2			3			3
Nondeductible employee meals	12			17			16
Impact of Tax Act	(5		)	(179		)	—
Income tax adjustment from AOCI (b)	—			—			180
State rate change	3			12			(12		)
Valuation allowance	(3		)	(16		)	20
Other, net	13			8			(26		)
	$	529		$	896		$	1,539

Current	$	14		$	(77	)	$	(92	)
Deferred	515			973			1,631
	$	529		$	896		$	1,539

United	2018			2017 (a)			2016 (a)
Income tax provision at statutory rate	$	559		$	1,065		$	1,321
State income taxes, net of federal income tax	29			30			38
Foreign tax rate differential	(84		)	(43		)	—
Global intangible low-taxed income	4			—			—
Foreign income taxes	2			3			3
Nondeductible employee meals	12			17			16
Impact of Tax Act	(5		)	(196		)	—
Income tax adjustment from AOCI (b)	—			—			180
State rate change	3			12			(12		)
Valuation allowance	(3		)	(16		)	20
Other, net	12			7			(25		)
	$	529		$	879		$	1,541

Current	$	14		$	(77	)	$	(92	)
Deferred	515			956			1,633
	$	529		$	879		$	1,541

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, 2018 and 2017 were as follows (in millions):



	UAL						United
	2018			2017			2018			2017
Deferred income tax asset (liability):
Federal and state net operating loss ("NOL") carryforwards	$	398		$	601		$	372		$	574
Deferred revenue	1,232			1,090			1,232			1,090
Employee benefits, including pension, postretirement and medical	885			1,051			885			1,051
Other	408			351			406			351
Less: Valuation allowance	(59		)	(63		)	(59		)	(63		)
Total deferred tax assets	$	2,864		$	3,030		$	2,836		$	3,003

Depreciation	$	(2,929	)	$	(2,431	)	$	(2,929	)	$	(2,431	)
Intangibles	(749		)	(803		)	(749		)	(803		)
Total deferred tax liabilities	$	(3,678	)	$	(3,234	)	$	(3,678	)	$	(3,234	)
Net deferred tax liability	$	(814	)	$	(204	)	$	(842	)	$	(231	)

Pension and Other Postretirement Plans (Tables)

12 Months Ended

Dec. 31, 2018

Retirement Benefits [Abstract]

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



	Pension Benefits
	Year Ended December 31, 2018			Year Ended December 31, 2017
Accumulated benefit obligation:	$	4,448		$	4,739

Change in projected benefit obligation:
Projected benefit obligation at beginning of year	$	5,852		$	5,253
Service cost	228			195
Interest cost	217			220
Actuarial (gain) loss	(601		)	525
Gross benefits paid and settlements	(292		)	(366		)
Other	(8		)	25
Projected benefit obligation at end of year	$	5,396		$	5,852

Change in plan assets:
Fair value of plan assets at beginning of year	$	3,932		$	3,355
Actual (loss) return on plan assets	(215		)	510
Employer contributions	413			419
Gross benefits paid and settlements	(292		)	(366		)
Other	(11		)	14
Fair value of plan assets at end of year	$	3,827		$	3,932
Funded status—Net amount recognized	$	(1,569	)	$	(1,920	)



	Pension Benefits
	December 31, 2018			December 31, 2017
Amounts recognized in the consolidated balance sheets consist of:
Noncurrent asset	$	13		$	9
Current liability	(6		)	(8		)
Noncurrent liability	(1,576		)	(1,921		)
Total liability	$	(1,569	)	$	(1,920	)

Amounts recognized in accumulated other comprehensive loss consist of:
Net actuarial loss	$	(1,382	)	$	(1,610	)
Prior service cost	(5		)	(1		)
Total accumulated other comprehensive loss	$	(1,387	)	$	(1,611	)

	Other Postretirement Benefits
	Year Ended December 31, 2018			Year Ended December 31, 2017
Change in benefit obligation:
Benefit obligation at beginning of year	$	1,710		$	1,687
Service cost	12			13
Interest cost	61			66
Plan participants' contributions	68			68
Benefits paid	(181		)	(178		)
Actuarial loss (gain)	(285		)	40
Other	6			14
Benefit obligation at end of year	$	1,391		$	1,710

Change in plan assets:
Fair value of plan assets at beginning of year	$	54		$	55
Actual return on plan assets	1			1
Employer contributions	111			108
Plan participants' contributions	68			68
Benefits paid	(181		)	(178		)
Fair value of plan assets at end of year	53			54
Funded status—Net amount recognized	$	(1,338	)	$	(1,656	)

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



	Pension Benefits
	December 31, 2018			December 31, 2017
Amounts recognized in the consolidated balance sheets consist of:
Noncurrent asset	$	13		$	9
Current liability	(6		)	(8		)
Noncurrent liability	(1,576		)	(1,921		)
Total liability	$	(1,569	)	$	(1,920	)

Amounts recognized in accumulated other comprehensive loss consist of:
Net actuarial loss	$	(1,382	)	$	(1,610	)
Prior service cost	(5		)	(1		)
Total accumulated other comprehensive loss	$	(1,387	)	$	(1,611	)

	Other Postretirement Benefits
	Year Ended December 31, 2018			Year Ended December 31, 2017
Change in benefit obligation:
Benefit obligation at beginning of year	$	1,710		$	1,687
Service cost	12			13
Interest cost	61			66
Plan participants' contributions	68			68
Benefits paid	(181		)	(178		)
Actuarial loss (gain)	(285		)	40
Other	6			14
Benefit obligation at end of year	$	1,391		$	1,710

Change in plan assets:
Fair value of plan assets at beginning of year	$	54		$	55
Actual return on plan assets	1			1
Employer contributions	111			108
Plan participants' contributions	68			68
Benefits paid	(181		)	(178		)
Fair value of plan assets at end of year	53			54
Funded status—Net amount recognized	$	(1,338	)	$	(1,656	)



	Other Postretirement Benefits
	December 31, 2018			December 31, 2017
Amounts recognized in the consolidated balance sheets consist of:
Current liability	$	(43	)	$	(54	)
Noncurrent liability	(1,295		)	(1,602		)
Total liability	$	(1,338	)	$	(1,656	)
Amounts recognized in accumulated other comprehensive income consist of:
Net actuarial gain	$	554		$	301
Prior service credit	170			208
Total accumulated other comprehensive income	$	724		$	509

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):



	2018		2017
Projected benefit obligation	$	5,196	$	5,637
Accumulated benefit obligation	4,286		4,567
Fair value of plan assets	3,614		3,709

Components Of Net Periodic Benefit Cost

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



	2018						2017						2016
	Pension Benefits			Other Postretirement Benefits			Pension Benefits			Other Postretirement Benefits			Pension Benefits			Other Postretirement Benefits
Service cost	$	228		$	12		$	195		$	13		$	112		$	19
Interest cost	217			61			220			66			200			86
Expected return on plan assets	(292		)	(2		)	(243		)	(2		)	(216		)	(2		)
Curtailment gain	—			—			—			—			—			(107		)
Amortization of unrecognized actuarial (gain) loss	130			(32		)	128			(33		)	76			(19		)
Amortization of prior service credits	—			(37		)	—			(37		)	—			(31		)
Other	1			—			5			—			5			—
Net periodic benefit cost (credit)	$	284		$	2		$	305		$	7		$	177		$	(54	)

Assumptions Used for Benefit Plans

The assumptions used for the benefit plans were as follows:



	Pension Benefits
Assumptions used to determine benefit obligations	2018		2017
Discount rate	4.20	%	3.65	%
Rate of compensation increase	3.89	%	3.89	%

Assumptions used to determine net expense
Discount rate	3.65	%	4.19	%
Expected return on plan assets	7.31	%	7.02	%
Rate of compensation increase	3.89	%	3.54	%

	Other Postretirement Benefits
Assumptions used to determine benefit obligations	2018		2017
Discount rate	4.30	%	3.63	%

Assumptions used to determine net expense
Discount rate	3.63	%	4.07	%
Expected return on plan assets	3.00	%	3.00	%
Health care cost trend rate assumed for next year	6.00	%	6.25	%
Rate to which the cost trend rate is assumed to decline (ultimate trend rate in 2023)	5.00	%	5.00	%

Allocation of Plan Assets

United's plan assets are allocated within the following guidelines:



	Percent of Total		Expected Long-Term Rate of Return
Equity securities	30-45	%	9.5	%
Fixed-income securities	30-40		5.8
Alternatives	10-25		7.3
Other	0-10		7.8

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):



	2018										2017
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	$	1,394	$	254	$	106	$	—	$	1,034	$	1,406	$	269	$	133	$	—	$	1,004
Fixed-income securities	1,431		—		605		21		805		1,470		—		834		18		618
Alternatives	596		—		—		134		462		637		—		—		139		498
Other investments	406		224		40		142		—		419		32		124		172		91
Total	$	3,827	$	478	$	751	$	297	$	2,301	$	3,932	$	301	$	1,091	$	329	$	2,211
Other Postretirement Benefit Plan Assets:
Deposit administration fund	$	53	$	—	$	—	$	53	$	—	$	54	$	—	$	—	$	54	$	—

Defined Benefit Plan Assets Measured at Fair Value Using Unobservable Inputs

The reconciliation of United's defined benefit plan assets measured at fair value using unobservable inputs (Level 3) for the years ended December 31, 2018 and 2017 is as follows (in millions):



	2018			2017
Balance at beginning of year	$	383		$	287
Actual return (loss) on plan assets:
Sold during the year	10			7
Held at year end	(21		)	16
Purchases, sales, issuances and settlements (net)	(22		)	73
Balance at end of year	$	350		$	383

Estimated Future Benefit Payments



	Pension		Other Postretirement		Other Postretirement— subsidy receipts
2019	$	329	$	100	$	5
2020	327		104		6
2021	353		108		6
2022	367		111		6
2023	379		113		7
Years 2024 – 2028	2,022		575		38

Participation in the IAM National Pension Plan



Pension Fund	IAM National Pension Fund
EIN/ Pension Plan Number	51-6031295 - 002
Pension Protection Act Zone Status (2018 and 2017)	Green Zone. Plans in the green zone are at least 80 percent funded.
FIP/RP Status Pending/Implemented	No
United's Contributions	$52 million, $50 million and $41 million in the years ended December 31, 2018, 2017 and 2016, respectively
Surcharge Imposed	No
Expiration Date of Collective Bargaining Agreement	N/A

Investments and Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2018

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):



	2018								2017
	Total		Level 1		Level 2		Level 3		Total		Level 1		Level 2		Level 3
Cash and cash equivalents	$	1,694	$	1,694	$	—	$	—	$	1,482	$	1,482	$	—	$	—
Short-term investments:
Corporate debt	1,023		—		1,023		—		958		—		958		—
Asset-backed securities	746		—		746		—		753		—		753		—
U.S. government and agency notes	108		—		108		—		113		—		113		—
Certificates of deposit placed through an account registry service ("CDARS")	75		—		75		—		120		—		120		—
Other fixed-income securities	116		—		116		—		188		—		188		—
Other investments measured at NAV	188		—		—		—		184		—		—		—
Restricted cash	105		105		—		—		109		109		—		—
Long-term investments:
Equity securities	249		249		—		—		99		99		—		—
Enhanced equipment trust certificates ("EETC")	18		—		—		18		22		—		—		22
Avianca Holdings S.A. ("AVH") Derivative Assets	11		—		—		11		—		—		—		—

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, issuance costs and origination costs:



	2018										2017
	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	$	13,445	$	13,450	$	—	$	9,525	$	3,925	$	13,268	$	13,787	$	—	$	10,115	$	3,672
Synergy Term Loan	478		422		—		—		422		—		—		—		—		—

Debt (Tables)

12 Months Ended

Dec. 31, 2018

Debt Disclosure [Abstract]

Summary of Long-Term Debt



(In millions)	At December 31,
	2018			2017
Secured
Notes payable, fixed interest rates of 0.0% to 9.52% (weighted average rate of 4.18% as of December 31, 2018), payable through 2030	$	8,811		$	8,661
Notes payable, floating interest rates of the London interbank offered rate ("LIBOR") plus 1.05% to 1.75%, payable through 2030	2,051			1,880
Term loan, LIBOR plus 1.75%, or alternative rate based on certain market rates plus 0.75%, due 2024	1,474			1,489
Unsecured
6.375% Senior Notes due 2018 (a)	—			300
6% Senior Notes due 2020 (a)	300			300
4.25% Senior Notes due 2022 (a)	400			400
5% Senior Notes due 2024 (a)	300			300
Other	300			101
	13,636			13,431
Less: unamortized debt discount, premiums and debt issuance costs	(191		)	(163		)
Less: current portion of long-term debt	(1,230		)	(1,565		)
Long-term debt, net	$	12,215		$	11,703

(a) UAL is the issuer of this debt. United is a guarantor.

Contractual Principal Payments under Outstanding Long-Term Debt Agreements



2019	$	1,230
2020	1,310
2021	1,300
2022	1,653
2023	703
After 2023	7,440
	$	13,636

Details of Pass Through Trusts

Certain details of the pass-through trusts with proceeds received from issuance of debt in 2018 are as follows (in millions, except stated interest rate):



EETC Date	Class	Principal		Final expected distribution date	Stated interest rate		Total debt recorded as of December 31, 2018		Proceeds received from issuance of debt during 2018		Remaining proceeds from issuance of debt to be received in future periods
February 2019	AA	$	717	August 2031	4.15	%	$	—	$	—	$	717
February 2019	A	296		August 2031	4.55	%	—		—		296
May 2018	B	226		March 2026	4.60	%	226		226		—
February 2018	AA	677		March 2030	3.50	%	677		677		—
February 2018	A	258		March 2030	3.70	%	258		258		—
		$	2,174				$	1,161	$	1,161	$	1,013

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
Various equipment notes and other notes payable	Secured by certain aircraft. The indentures contain events of default that are customary for aircraft financing, including in certain cases cross default to other related aircraft.
Credit Agreement	Secured by certain of United's international route authorities, specified take-off and landing slots at certain airports and certain other assets. The Credit Agreement requires 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 obligations under the Credit Agreement of 1.6 to 1.0 at all times. The Credit Agreement contains covenants that, among other things, restrict the ability of UAL and its restricted subsidiaries (as defined in the Credit Agreement) to incur additional indebtedness and to pay dividends on or repurchase stock, although, as of December 31, 2018, the Company had ample ability under these restrictions to repurchase stock under the Company's share repurchase program. The Credit Agreement contains events of default customary for this type of financing, including a cross default and cross acceleration provision to certain other material indebtedness of the Company.
6% Senior Notes due 2020 4.25% Senior Notes due 2022 5% Senior Notes due 2024	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 pay dividends on or repurchase stock, although the Company currently has ample ability under these restrictions to repurchase stock under the Company's share repurchase program.

- 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/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21475-112644

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=75038535&loc=d3e64711-112823

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(e),(f))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=64930739&loc=d3e28878-108400

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21538-112644

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21506-112644

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 1A
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28541-108399

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28551-108399

Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21521-112644

+ Details

Leases and Capacity Purchase Agreements (Tables)

12 Months Ended

Dec. 31, 2018

Leases [Abstract]

Future Minimum Lease Payments for Capital and Operating Leases



	Capital Leases (b)			Facility and Other Operating Leases		Aircraft Operating Leases
2019	$	308		$	1,330	$	845
2020	170			1,351		682
2021	147			1,107		583
2022	123			970		407
2023	104			953		379
After 2023	1,268			7,029		1,160
Minimum lease payments (a)	$	2,120		$	12,740	$	4,056
Imputed interest	(837		)
Present value of minimum lease payments	1,283
Current portion	(149		)
Long-term obligations under capital leases	$	1,134

(a) Includes fair value lease and deferred financing fee balances, which are being amortized over the terms of their respective leases.

Future Lease Payment Under Terms of Capacity Purchase Agreement

Based on these assumptions as of December 31, 2018, our future payments through the end of the terms of our CPAs are presented in the table below (in billions):



2019	$	2.2
2020	2.0
2021	1.8
2022	1.4
2023	0.8
After 2023	3.1
	$	11.3

Commitments and Contingencies (Tables)

12 Months Ended

Dec. 31, 2018

Commitments and Contingencies Disclosure [Abstract]

Summary of Commitments to Purchase Aircraft



2019	$	4.2
2020	5.3
2021	3.5
2022	2.8
2023	1.9
After 2023	7.0
	$	24.7

As of December 31, 2018, United had firm commitments and options to purchase aircraft from The Boeing Company ("Boeing"), Airbus S.A.S. ("Airbus") and Embraer S.A. ("Embraer") presented in the table below:



Aircraft Type		Number of Firm Commitments (a)
Airbus A350		45
Boeing 737 MAX		175
Boeing 777-300ER		4
Boeing 787		24
Embraer E175		25
(a) United also has options and purchase rights for additional aircraft.

Special Charges (Tables)

12 Months Ended

Dec. 31, 2018

Business Combinations [Abstract]

Components of Special Charges

Special charges in the statements of consolidated operations consisted of the following for the years ended December 31 (in millions):



Operating:	2018			2017 (a)			2016 (a)
Impairment of assets	$	377		$	25		$	412
Termination of an engine maintenance service agreement	64			—			—
Severance and benefit costs	41			116			37
Cleveland airport lease restructuring	—			—			74
Labor agreement costs	—			—			171
(Gains) losses on sale of assets and other special charges	5			35			51
Total operating special charges	487			176			745
Nonoperating:
Postretirement curtailment gain	—			—			(107		)
Gains on extinguishment of debt and other	—			—			(1		)
Total operating and nonoperating special charges before income taxes	487			176			637
Nonoperating mark-to-market ("MTM") losses on financial instruments	5			—			—
Total special charges and MTM losses on financial instruments	492			176			637
Income tax benefit	(110		)	(63		)	(229		)
Income tax adjustments (Note 7)	(5		)	(179		)	180
Total special charges and MTM losses on financial instruments, net of income taxes and income tax adjustments	$	377		$	(66	)	$	588

Activity related to the accruals for severance and medical costs and future lease payments on permanently grounded aircraft is as follows (in millions):



	Severance/ Benefit Costs			Permanently Grounded Aircraft
Balance at December 31, 2015	$	27		$	78
Accrual and related adjustments	37			(17		)
Payments	(50		)	(20		)
Balance at December 31, 2016	14			41
Accrual	116			(4		)
Payments	(93		)	(15		)
Balance at December 31, 2017	37			22
Accrual	41			(7		)
Payments	(53		)	(3		)
Balance at December 31, 2018	$	25		$	12

Selected Quarterly Financial Data (Unaudited) (Tables)

12 Months Ended

Dec. 31, 2018

Quarterly Financial Information Disclosure [Abstract]

Summary of Selected Quarterly Financial Data



UAL	Quarter Ended
(In millions, except per share amounts)	March 31		June 30		September 30		December 31
2018
Operating revenue	$	9,032	$	10,777	$	11,003	$	10,491
Income from operations	276		1,161		1,203		652
Net income	147		684		836		462
Basic earnings per share	0.52		2.49		3.07		1.71
Diluted earnings per share	0.52		2.48		3.06		1.70

2017 (a)
Operating revenue	$	8,426	$	10,008	$	9,899	$	9,451
Income from operations	320		1,437		1,138		776
Net income	99		821		645		579
Basic earnings per share	0.32		2.67		2.15		1.99
Diluted earnings per share	0.32		2.67		2.15		1.98

Impact of Significant Items on Quarterly Results



UAL	Quarter Ended
(In millions, except per share amounts)	March 31		June 30		September 30		December 31
2018
Operating revenue	$	9,032	$	10,777	$	11,003	$	10,491
Income from operations	276		1,161		1,203		652
Net income	147		684		836		462
Basic earnings per share	0.52		2.49		3.07		1.71
Diluted earnings per share	0.52		2.48		3.06		1.70

2017 (a)
Operating revenue	$	8,426	$	10,008	$	9,899	$	9,451
Income from operations	320		1,437		1,138		776
Net income	99		821		645		579
Basic earnings per share	0.32		2.67		2.15		1.99
Diluted earnings per share	0.32		2.67		2.15		1.98



	Quarter Ended
	March 31			June 30			September 30			December 31
2018
Operating:
Impairment of assets	$	23		$	111		$	11		$	232
Termination of an engine maintenance service agreement	—			—			—			64
Severance and benefit costs	14			11			9			7
(Gains) losses on sale of assets and other special charges	3			7			(3		)	(2		)
Total operating special charges	40			129			17			301
Nonoperating:
Nonoperating mark-to-market ("MTM") (gains) losses on financial instruments	(45		)	135			(29		)	(56		)
Total special charges and MTM (gains) losses on financial instruments	(5		)	264			(12		)	245
Income taxes:
Income tax expense (benefit) related to special charges and MTM gains and losses on financial instruments	1			(59		)	3			(55		)
Income tax adjustments	—			—			—			(5		)
Total special charges and MTM (gains) losses on financial instruments, net of tax	$	(4	)	$	205		$	(9	)	$	185

2017 (a)
Operating:
Severance and benefit costs	$	37		$	41		$	23		$	15
Impairment of assets	—			—			15			10
(Gains) losses on sale of assets and other special charges	14			3			12			6
Total operating special charges	51			44			50			31
Income taxes:
Income tax benefit related to special charges	(18		)	(16		)	(18		)	(11		)
Income tax adjustments	—			—			—			(179		)
Total operating special charges, net of income taxes and income tax adjustments	$	33		$	28		$	32		$	(159	)

Significant Accounting Policies - Operating Revenue by Principal Geographic Region (Details) - USD ($)
$ in Millions

3 Months Ended

12 Months Ended

Dec. 31, 2018

Sep. 30, 2018

Jun. 30, 2018

Mar. 31, 2018

Dec. 31, 2017

Sep. 30, 2017

Jun. 30, 2017

Mar. 31, 2017

Dec. 31, 2018

Dec. 31, 2017

Dec. 31, 2016

Domestic (U.S. and Canada)

$ 10,491

$ 11,003

$ 10,777

$ 9,032

$ 9,451

$ 9,899

$ 10,008

$ 8,426

$ 41,303

$ 37,784

^[1]

$ 36,558

^[1]

25,552

23,114

22,151

Atlantic

7,103

6,340

6,194

Pacific

5,188

4,914

4,984

Latin America

Summary Of Significant Accounting Policies [Line Items]

$ 3,460

$ 3,416

$ 3,229

[1]

Amounts adjusted due to the adoption of Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606) and Accounting Standards Update No. 2017-07, Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost. See Note 1 to the financial statements contained in Part II, Item 8 of this report for additional information.

Significant Accounting Policies - Narrative (Details) - USD ($)
$ in Millions

3 Months Ended

12 Months Ended

Dec. 31, 2018

Sep. 30, 2018

Jun. 30, 2018

Mar. 31, 2018

Dec. 31, 2017

Sep. 30, 2017

Jun. 30, 2017

Mar. 31, 2017

Dec. 31, 2018

Dec. 31, 2017

Dec. 31, 2016

Jan. 01, 2018

Jan. 01, 2017

Period of member account inactivity at which miles expire

$ 10,491

$ 11,003

$ 10,777

$ 9,032

$ 9,451

$ 9,899

$ 10,008

$ 8,426

$ 41,303

$ 37,784

^[1]

$ 36,558

^[1]

18 months

Carrying value of computer software

$ 359

$ 345

$ 359

345

Residual value

10.00%

Advertising expense

$ 211

217

220

Reclassification to retained earnings upon adoption of accounting standard

$ (14)

Retained Earnings (Accumulated Deficit)

Summary Of Significant Accounting Policies [Line Items]

Reclassification to retained earnings upon adoption of accounting standard

$ 6

$ (14)

ASU 2016-01 | Retained Earnings (Accumulated Deficit)

Summary Of Significant Accounting Policies [Line Items]

Reclassification to retained earnings upon adoption of accounting standard

$ 6

Minimum

Summary Of Significant Accounting Policies [Line Items]

Frequent flier program expiration period

1 year

Maximum

Summary Of Significant Accounting Policies [Line Items]

Frequent flier program expiration period

8 years

Aircraft Seats | Minimum

Summary Of Significant Accounting Policies [Line Items]

Summary Of Significant Accounting Policies [Line Items]

10 years

Aircraft Seats | Maximum

Aircraft and Aircraft Spare Parts

15 years

Summary Of Significant Accounting Policies [Line Items]

Residual value

10.00%

Computer Software

Summary Of Significant Accounting Policies [Line Items]

Depreciation expense

$ 122

117

108

Computer Software | Minimum

Summary Of Significant Accounting Policies [Line Items]

Computer Software | Maximum

5 years

Summary Of Significant Accounting Policies [Line Items]

Summary Of Significant Accounting Policies [Line Items]

15 years

Passenger Revenue

Ancillary fees

$ 2,200

2,000

1,900

Passenger Revenue

Summary Of Significant Accounting Policies [Line Items]

Summary Of Significant Accounting Policies [Line Items]

37,706

34,460

^[1]

33,429

^[1]

Other Operating Revenue

Other Operating Revenue | Chase and Other Partner Agreements

2,360

2,210

^[1]

2,195

^[1]

Summary Of Significant Accounting Policies [Line Items]

Transportation Advance Ticket Arrangement | Passenger Revenue

2,000

1,800

$ 1,700

Summary Of Significant Accounting Policies [Line Items]

$ 3,100

$ 2,900

[1]

Significant Accounting Policies - Impact of the Adoption of the New Revenue Standard and the New Retirement Standard (Details) - USD ($)
$ / shares in Units, $ in Millions

3 Months Ended

12 Months Ended

Dec. 31, 2018

Sep. 30, 2018

Jun. 30, 2018

Mar. 31, 2018

Dec. 31, 2017

Sep. 30, 2017

Jun. 30, 2017

Mar. 31, 2017

Dec. 31, 2018

Dec. 31, 2017

Dec. 31, 2016

$ 10,491

$ 11,003

$ 10,777

$ 9,032

$ 9,451

$ 9,899

$ 10,008

$ 8,426

$ 41,303

$ 37,784

^[1]

$ 36,558

^[1]

38,011

34,113

^[1]

32,214

^[1]

652

1,203

1,161

276

776

1,138

1,437

320

3,292

3,671

^[1]

4,344

^[1]

(634)

(631)

^[1]

(571)

^[1]

2,658

3,040

^[1]

3,773

^[1]

529

896

^[1]

1,539

^[1]

$ 462

$ 836

$ 684

$ 147

$ 579

$ 645

$ 821

$ 99

$ 2,129

$ 2,144

^{[1],[2],[3],[4]}

$ 2,234

^{[1],[2],[3],[4]}

$ 1.71

$ 3.07

$ 2.49

$ 0.52

$ 1.99

$ 2.15

$ 2.67

$ 0.32

$ 7.73

$ 7.08

^[1]

$ 6.77

^[1]

$ 1.70

$ 3.06

$ 2.48

$ 0.52

$ 1.98

$ 2.15

$ 2.67

$ 0.32

$ 7.70

$ 7.06

^[1]

$ 6.76

^[1]

$ 913

$ 1,071

^[5]

$ 913

$ 1,071

^[5]

4,381

3,940

^[5]

4,381

3,940

^[5]

2,286

2,192

^[5]

2,286

2,192

^[5]

619

576

^[5]

619

576

^[5]

2,719

2,591

^[5]

2,719

2,591

^[5]

814

204

^[5]

814

204

^[5]

$ 6,668

4,549

^[5]

6,668

4,549

^[5]

As Previously Reported

1,051

3,876

2,176

569

2,565

225

4,621

Passenger revenue

37,706

34,460

^[1]

$ 33,429

^[1]

Cargo

1,237

1,114

^[1]

934

^[1]

Other operating revenue

$ 2,360

2,210

^[1]

2,195

^[1]

As Previously Reported

37,736

36,556

34,238

32,218

3,498

4,338

(499)

(519)

2,999

3,819

868

1,556

$ 2,131

$ 2,263

$ 7.04

$ 6.86

As Previously Reported | Passenger revenue

$ 7.02

$ 6.85

As Previously Reported | Cargo

$ 32,404

$ 31,457

As Previously Reported | Other operating revenue

1,035

876

ASU 2014-09 | New Revenue Standard Adjustments

4,297

4,223

(21)

$ (72)

(72)

ASU 2014-09 | Adjustment

(21)

(12)

(28)

(60)

(46)

(17)

$ 13

$ (29)

$ 0.04

$ (0.09)

ASU 2014-09 | Adjustment | Passenger revenue

$ 0.04

$ (0.09)

ASU 2014-09 | Adjustment | Cargo

$ 2,056

$ 1,972

ASU 2014-09 | Adjustment | Other operating revenue

(2,087)

(2,028)

ASU 2017-07 | Adjustment

(104)

104

(8)

(104)

$ 0

$ 0.00

ASU 2017-07 | Adjustment | Passenger revenue

$ 0.00

ASU 2017-07 | Adjustment | Cargo

$ 0

ASU 2017-07 | Adjustment | Other operating revenue

$ 0

[1]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606) and Accounting Standards Update No. 2017-07, Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost. See Note 1 to the financial statements contained in Part II, Item 8 of this report for additional information.
[2]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606). See Note 1 to the financial statements contained in Part II, Item 8 of this report for additional information.
[3]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606). See Note 1 to the financial statements contained in Part II, Item 8 of this report for additional information.
[4]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606). See Note 1 to the financial statements contained in Part II, Item 8 of this report for additional information.
[5]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606). See Note 1 to the financial statements contained in Part II, Item 8 of this report for additional information.

Significant Accounting Policies - Roll Forward of Frequent Flier Deferred Revenue (Details) - Transportation Advance Ticket Arrangement - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Movement in Deferred Revenue [Roll Forward]
Total Frequent flyer deferred revenue - beginning balance	$ 4,783	$ 4,889
Total miles awarded	2,451	2,077
Travel miles redeemed (Passenger revenue)	(2,068)	(2,004)
Non-travel miles redeemed (Other operating revenue)	(161)	(179)
Total Frequent flyer deferred revenue - ending balance	$ 5,005	$ 4,783

Significant Accounting Policies - Estimated Useful Lives of Property and Equipment (Details)	12 Months Ended
	Dec. 31, 2018
Aircraft and related rotable parts \| Minimum
Property, Plant and Equipment [Line Items]
Estimated useful life	25 years
Aircraft 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

Significant Accounting Policies - Reconciliation of Cash, Cash Equivalents and Restricted Cash (Details) - USD ($)
$ in Millions

Dec. 31, 2018

Dec. 31, 2017

Dec. 31, 2016

Dec. 31, 2015

$ 1,694

$ 1,482

^[1]

$ 2,179

Total cash, cash equivalents and restricted cash shown in the statement of consolidated cash flows

105

^[1]

124

1,799

1,591

^[2]

2,303

^[2]

$ 3,212

^[2]

Prepaid Expenses and Other

1,688

1,476

^[3]

2,173

Total cash, cash equivalents and restricted cash shown in the statement of consolidated cash flows

105

^[3]

124

1,793

1,585

^[4]

2,297

^[4]

$ 3,206

^[4]

United Airlines, Inc. | Prepaid Expenses and Other

$ 0

$ 18

$ 0

[1]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606). See Note 1 to the financial statements contained in Part II, Item 8 of this report for additional information.
[2]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606). See Note 1 to the financial statements contained in Part II, Item 8 of this report for additional information.
[3]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606). See Note 1 to the financial statements contained in Part II, Item 8 of this report for additional information.
[4]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606). See Note 1 to the financial statements contained in Part II, Item 8 of this report for additional information.

Significant Accounting Policies - Expected Impact of the Adoption of the New Lease Standard (Details) - USD ($)
$ / shares in Units, $ in Millions

3 Months Ended

12 Months Ended

Dec. 31, 2018

Sep. 30, 2018

Jun. 30, 2018

Mar. 31, 2018

Dec. 31, 2017

Sep. 30, 2017

Jun. 30, 2017

Mar. 31, 2017

Dec. 31, 2018

Dec. 31, 2017

Dec. 31, 2016

^[2]

Receivables, less allowance for doubtful accounts (2018—$8; 2017—$7)

$ 1,346

$ 1,340

^[1]

$ 1,346

$ 1,340

^[1]

913

1,071

^[1]

913

1,071

^[1]

Less-Accumulated depreciation and amortization (owned)

7,919

6,946

^[1]

7,919

6,946

^[1]

(12,760)

(11,159)

^[1]

(12,760)

(11,159)

^[1]

Less-Accumulated amortization

1,029

1,151

^[1]

1,029

1,151

^[1]

(654)

(777)

^[1]

(654)

(777)

^[1]

Current maturities of capital leases

149

128

^[1]

149

128

^[1]

Long-term obligations under finance leases

619

576

^[1]

619

576

^[1]

1,134

996

1,134

996

814

204

^[1]

814

204

^[1]

1,832

^[1]

1,832

^[1]

6,668

4,549

^[1]

6,668

4,549

^[1]

2,601

2,232

^[2]

$ 2,197

2,359

2,240

^[2]

2,165

2,240

2,149

^[2],[3]

1,977

^[3]

38,011

34,113

^[2]

32,214

652

$ 1,203

$ 1,161

$ 276

776

$ 1,138

$ 1,437

$ 320

3,292

3,671

^[2]

4,344

(729)

(671)

^[2]

(674)

^[2]

(634)

(631)

^[2]

(571)

2,658

3,040

^[2]

3,773

529

896

^[2]

1,539

$ 462

$ 836

$ 684

$ 147

$ 579

$ 645

$ 821

$ 99

$ 2,129

$ 2,144

^{[2],[3],[4],[5]}

$ 2,234

^[3],[4],[5]

$ 1.71

$ 3.07

$ 2.49

$ 0.52

$ 1.99

$ 2.15

$ 2.67

$ 0.32

$ 7.73

$ 7.08

^[2]

$ 6.77

$ 1.70

$ 3.06

$ 2.48

$ 0.52

$ 1.98

$ 2.15

$ 2.67

$ 0.32

$ 7.70

$ 7.06

^[2]

$ 6.76

ASU 2016-02

Receivables, less allowance for doubtful accounts (2018—$8; 2017—$7)

$ 1,426

$ 1,466

$ 1,426

$ 1,466

733

863

733

863

Less-Accumulated depreciation and amortization (owned)

6,878

6,024

6,878

6,024

(12,620)

(11,067)

(12,620)

(11,067)

Flight equipment (Finance leases)

992

940

992

940

Less-Accumulated amortization

(646)

(608)

(646)

(608)

Current maturities of finance leases

123

Current maturities of operating leases

719

949

719

949

Long-term obligations under finance leases

553

518

553

518

224

230

224

230

Long-term obligations under operating leases

5,276

5,789

5,276

5,789

828

220

828

220

1,010

1,021

1,010

1,021

6,715

4,603

6,715

4,603

2,649

2,268

2,449

2,310

2,165

2,096

38,074

34,166

3,229

3,618

(670)

(626)

(581)

(595)

2,648

3,023

526

880

$ 2,122

$ 2,143

$ 7.70

$ 7.08

ASU 2016-02 | Flight Equipment

$ 7.67

$ 7.06

ASU 2016-02 | Other Property and Equipment

2,380

3,102

$ 2,380

$ 3,102

ASU 2016-02 | New Lease Standard Adjustments

2,882

2,975

2,882

2,975

Receivables, less allowance for doubtful accounts (2018—$8; 2017—$7)

126

(180)

(208)

(180)

(208)

Less-Accumulated depreciation and amortization (owned)

(1,041)

(922)

(1,041)

(922)

140

Flight equipment (Finance leases)

(37)

(211)

(37)

(211)

Less-Accumulated amortization

169

Current maturities of finance leases

(26)

(50)

(26)

(50)

Current maturities of operating leases

719

949

719

949

Long-term obligations under finance leases

(66)

(58)

(66)

(58)

(910)

(766)

(910)

(766)

Long-term obligations under operating leases

5,276

5,789

5,276

5,789

(822)

(811)

(822)

(811)

(75)

(53)

(63)

(53)

(5)

(10)

(10)

(17)

(3)

(16)

$ (7)

$ (1)

$ (0.03)

$ 0.00

ASU 2016-02 | New Lease Standard Adjustments | Flight Equipment

$ (0.03)

$ 0.00

ASU 2016-02 | New Lease Standard Adjustments | Other Property and Equipment

2,380

3,102

$ 2,380

$ 3,102

Goodwill and Intangible Assets Disclosure [Abstract]

$ 2,882

$ 2,975

$ 2,882

$ 2,975

[1]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606). See Note 1 to the financial statements contained in Part II, Item 8 of this report for additional information.
[2]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606) and Accounting Standards Update No. 2017-07, Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost. See Note 1 to the financial statements contained in Part II, Item 8 of this report for additional information.
[3]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606). See Note 1 to the financial statements contained in Part II, Item 8 of this report for additional information.
[4]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606). See Note 1 to the financial statements contained in Part II, Item 8 of this report for additional information.
[5]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606). See Note 1 to the financial statements contained in Part II, Item 8 of this report for additional information.

Goodwill and Other Intangible Assets - Information about Goodwill and Other Intangible Assets (Details) - USD ($)
$ in Millions

Dec. 31, 2018

Dec. 31, 2017

Goodwill

$ 4,523

^[1]

1,756

1,757

Indefinite-lived Intangible Assets [Line Items]

1,380

1,313

^[1]

Indefinite-lived Intangible Assets [Line Items]

2,783

3,095

Route authorities

Indefinite-lived Intangible Assets [Line Items]

1,240

1,562

Airport slots and gates

Indefinite-lived Intangible Assets [Line Items]

546

536

Tradenames and logos

Indefinite-lived Intangible Assets [Line Items]

593

Alliances

404

Frequent flyer database

1,177

884

832

Hubs

145

Contracts

120

121

106

103

Patents and tradenames

108

108

Airport slots and gates

109

Earnings available to common stockholders

$ 88

$ 84

[1]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606). See Note 1 to the financial statements contained in Part II, Item 8 of this report for additional information.

Goodwill and Other Intangible Assets - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Goodwill and Intangible Assets Disclosure [Abstract]
Amortization expense	$ 67	$ 79	$ 90
Projected amortization expense:
Projected amortization expense in 2019	61
Projected amortization expense in 2020	55
Projected amortization expense in 2021	50
Projected amortization expense in 2022	40
Projected amortization expense in 2023	$ 37

Common Stockholders' Equity and Preferred Securities (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Equity [Abstract]
Number of shares repurchased (in shares)	17,500,000
Repurchases of common stock	$ 1,250,000,000	$ 1,844,000,000	$ 2,607,000,000
Share repurchase program additional amount authorized		$ 3,000,000,000.0
Amount remaining under repurchase programs	$ 1,800,000,000
Common stock reserved for future issuance (in shares)	10,000,000
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

Earnings Per Share (Details) - USD ($)
$ / shares in Units, shares in Millions, $ in Millions

3 Months Ended

12 Months Ended

Dec. 31, 2018

Sep. 30, 2018

Jun. 30, 2018

Mar. 31, 2018

Dec. 31, 2017

Sep. 30, 2017

Jun. 30, 2017

Mar. 31, 2017

Dec. 31, 2018

Dec. 31, 2017

Dec. 31, 2016

Earnings Per Share [Abstract]

$ 2,129

$ 2,144

$ 2,234

Basic weighted-average shares outstanding (in shares)

275.5

302.7

329.9

Effect of employee stock awards (in shares)

1.2

0.9

0.4

Diluted weighted-average shares outstanding (in shares)

276.7

303.6

330.3

$ 1.71

$ 3.07

$ 2.49

$ 0.52

$ 1.99

$ 2.15

$ 2.67

$ 0.32

$ 7.73

$ 7.08

^[1]

$ 6.77

^[1]

AOCI Attributable to Parent, Net of Tax [Roll Forward]

$ 1.70

$ 3.06

$ 2.48

$ 0.52

$ 1.98

$ 2.15

$ 2.67

$ 0.32

$ 7.70

$ 7.06

^[1]

$ 6.76

^[1]

[1]

Share-Based Compensation Plans - Narrative (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of RSUs and restricted stock vested in period	$ 70.0	$ 76.0	$ 80.0
Stock option awards outstanding (in shares)	400
Stock option awards exercisable (in shares)	200
Weighted-average exercise price of stock options outstanding (in dollars per share)	$ 55.62
Weighted-average exercise price of stock options exercisable (in dollars per share)	$ 47.07
Intrinsic value of stock options outstanding	$ 12.0
Intrinsic value of stock options exercisable	$ 6.0
Weighted average remaining contractual lives of stock options outstanding	5 years 9 months 18 days
Weighted average remaining contractual lives of stock options exercisable	3 years 9 months 18 days
RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards granted (in shares)	1,800
Liabilities related to share based payments	$ 51.0
Payment related to share-based liabilities	$ 28.0	$ 50.0	$ 69.0
Time-Vested RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards granted (in shares)	1,100
Vesting period	3 years
Number of days used to compute performance period average closing price of restricted stock units	20 days
Performance-Based RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards granted (in shares)	700
Vesting period	3 years
Number of days used to compute performance period average closing price of restricted stock units	20 days
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options granted (in shares)		36	100
Weighted-average grant date exercise price of stock options granted (in dollars per share)		$ 77.56
Weighted-average grant date fair value of stock options granted		$ 0.7
Stock Options \| Exercise Prices at a 25% Premium of the Grant Date Fair Value
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options granted (in shares)			300
Weighted-average grant date exercise price of stock options granted (in dollars per share)			$ 56.19
Weighted-average grant date fair value of stock options granted			$ 2.3
Percentage of premium of the grant date fair market value			25.00%

Share-Based Compensation Plans - Information Related to Share-Based Compensation Plan Cost (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation cost	$ 101	$ 73	$ 70
RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation cost	98	63	58
Restricted stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation cost	2	8	11
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation cost	$ 1	$ 2	$ 1

Share-Based Compensation Plans - Summary of Unearned Compensation and Weighted-Average Remaining Period to Recognize Costs (Details) $ in Millions	12 Months Ended
	Dec. 31, 2018 USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unearned compensation	$ 68
RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unearned compensation	$ 66
Weighted average remaining period	1 year 7 months 6 days
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unearned compensation	$ 2
Weighted average remaining period	2 years 7 months 6 days

Share-Based Compensation Plans - Summary of RSU and Restricted Stock Activity (Details) - $ / shares shares in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Equity Awards - RSUs
Awards
Outstanding (in shares)	1.4	0.8	0.0
Granted (in shares)	1.1	1.0	0.9
Vested (in shares)	(0.5)	(0.3)	0.0
Forfeited (in shares)	(0.2)	(0.1)	(0.1)
Outstanding (in shares)	1.8	1.4	0.8
Weighted- Average Grant Price
Outstanding (in dollars per share)	$ 63.99	$ 51.67	$ 0.00
Granted (in dollars per share)	67.74	71.68	51.60
Vested (in dollars per share)	63.02	51.81	0.00
Forfeited (in dollars per share)	67.34	57.49	50.57
Outstanding (in dollars per share)	$ 66.29	$ 63.99	$ 51.67
Liability Awards - RSUs
Awards
Outstanding (in shares)	1.8	2.1	2.6
Granted (in shares)	0.7	0.6	1.0
Vested (in shares)	(0.5)	(0.7)	(1.4)
Forfeited (in shares)	(0.1)	(0.2)	(0.1)
Outstanding (in shares)	1.9	1.8	2.1
Restricted Stock
Awards
Outstanding (in shares)	0.3	0.5	0.3
Granted (in shares)	0.0	0.0	0.4
Vested (in shares)	(0.2)	(0.2)	(0.1)
Forfeited (in shares)	0.0	0.0	(0.1)
Outstanding (in shares)	0.1	0.3	0.5
Weighted- Average Grant Price
Outstanding (in dollars per share)	$ 52.30	$ 52.00	$ 48.68
Granted (in dollars per share)	0.00	0.00	50.63
Vested (in dollars per share)	53.24	51.60	41.47
Forfeited (in dollars per share)	0.00	0.00	53.42
Outstanding (in dollars per share)	$ 51.17	$ 52.30	$ 52.00

Accumulated Other Comprehensive Income (Loss) - Components of the Company's AOCI (Details) - USD ($)
$ in Millions

12 Months Ended

Dec. 31, 2018

Dec. 31, 2017

Dec. 31, 2016

Balance, deferred taxes

$ (39)

$ 26

$ (256)

Other comprehensive income (loss) before reclassifications, deferred taxes

8,734

^[1]

8,574

8,966

(83)

187

Other comprehensive income (loss) before reclassifications, net of tax

289

(239)

(334)

Amounts reclassified from accumulated other comprehensive income, deferred taxes

(13)

(21)

Amounts reclassified from accumulated other comprehensive income, net of tax

336

Reclassification of stranded tax effects, tax

(118)

Amounts reclassified to retained earnings, deferred taxes

(1)

Amounts reclassified to retained earnings, net of taxes

Balance, deferred taxes

(136)

(39)

Decrease (increase) in prior service credits

9,995

8,734

^[1]

8,574

(30)

Decrease (increase) in actuarial losses

380

306

560

Accumulated Other Comprehensive Income (Loss)

AOCI Attributable to Parent, Net of Tax [Roll Forward]

Reclassification of stranded tax effects

(1,147)

(829)

(831)

(118)

Pension and Other Postretirement Liabilities

(803)

(1,147)

(829)

AOCI Attributable to Parent, Net of Tax [Roll Forward]

Other comprehensive income (loss) before reclassifications, before tax

(1,102)

(854)

(363)

377

(306)

(517)

Amounts reclassified from accumulated other comprehensive income, before tax

Amounts reclassified to retained earnings, before tax

Fuel Derivatives Contracts

(663)

(1,102)

(854)

AOCI Attributable to Parent, Net of Tax [Roll Forward]

Other comprehensive income (loss) before reclassifications, before tax

(2)

(215)

(4)

Amounts reclassified from accumulated other comprehensive income, before tax

217

Amounts reclassified to retained earnings, before tax

AOCI Attributable to Parent, Net of Tax [Roll Forward]

(2)

Investments and Other

Other comprehensive income (loss) before reclassifications, before tax

(6)

(5)

(7)

Amounts reclassified from accumulated other comprehensive income, before tax

(2)

Amounts reclassified to retained earnings, before tax

Accumulated Other Comprehensive Income (Loss) [Line Items]

$ (4)

$ (6)

$ 1

[1]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606). See Note 1 to the financial statements contained in Part II, Item 8 of this report for additional information.

Accumulated Other Comprehensive Income (Loss) - Details about AOCI Components (Details) - USD ($)
$ in Millions

12 Months Ended

Dec. 31, 2018

Dec. 31, 2017

Dec. 31, 2016

$ 9,307

$ 6,913

^[1]

$ 5,813

^[1]

Fuel derivative contracts | Amount Reclassified from AOCI to Income

101

^[1]

Accumulated Other Comprehensive Income (Loss) [Line Items]

Pension and Postretirement liabilities and other | Amount Reclassified from AOCI to Income

217

Accumulated Other Comprehensive Income (Loss) [Line Items]

Investments and other | Amount Reclassified from AOCI to Income

Accumulated Other Comprehensive Income (Loss) [Line Items]

$ 0

$ (2)

[1]

Income Taxes - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
Income Taxes - Narrative (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Taxes [Line Items]
Federal statutory income tax rate	21.00%
Income tax benefit for the one-time transition tax	$ 4
Unrecognized tax benefits	39	$ 21	$ 74
Unrecognized tax benefits that would impact effective tax rate if recognized	39
2030
Income Taxes [Line Items]
NOL carry forwards	600
Thereafter
Income Taxes [Line Items]
NOL carry forwards	1,000
Federal
Income Taxes [Line Items]
NOL carry forwards	1,600
State
Income Taxes [Line Items]
NOL carry forwards	83
NOL carry forwards, valuation allowance	$ 48

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, 2018

Dec. 31, 2017

Dec. 31, 2016

Sep. 30, 2015

Income tax provision at statutory rate

$ 558

$ 1,064

$ 1,320

State income taxes, net of federal income tax benefit

Foreign tax rate differential

(84)

(43)

Global intangible low-taxed income

Foreign income taxes

Nondeductible employee meals

Impact of Tax Act

(5)

(179)

Income tax adjustment from AOCI

180

State rate change

(12)

Valuation allowance

(3)

(16)

Income tax expense (benefit)

(26)

529

896

^[1]

1,539

^[1]

Current

(77)

(92)

Deferred

515

973

^[2]

1,631

^[2]

AOCI

Income tax adjustment from AOCI

180

AOCI | Pension and Other Postretirement Liabilities

$ 465

AOCI | Designated as Hedging Instrument | Fuel

285

$ 180

Income tax provision at statutory rate

559

1,065

1,321

State income taxes, net of federal income tax benefit

Foreign tax rate differential

(84)

(43)

Global intangible low-taxed income

Foreign income taxes

Nondeductible employee meals

Impact of Tax Act

(5)

(196)

Income tax adjustment from AOCI

180

State rate change

(12)

Valuation allowance

(3)

(16)

Income tax expense (benefit)

(25)

529

879

^[3]

1,541

^[3]

Current

(77)

(92)

Deferred

515

956

^[4]

$ 1,633

^[4]

$ 59

$ 63

[1]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606) and Accounting Standards Update No. 2017-07, Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost. See Note 1 to the financial statements contained in Part II, Item 8 of this report for additional information.
[2]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606). See Note 1 to the financial statements contained in Part II, Item 8 of this report for additional information.
[3]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606) and Accounting Standards Update No. 2017-07, Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost. See Note 1 to the financial statements contained in Part II, Item 8 of this report for additional information.
[4]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606). See Note 1 to the financial statements contained in Part II, Item 8 of this report for additional information.

Income Taxes - Temporary Differences and Carryforwards Giving Rise to Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Deferred income tax asset (liability):
Federal and state net operating loss (NOL) carryforwards	$ 398	$ 601
Deferred revenue	1,232	1,090
Employee benefits, including pension, postretirement and medical	885	1,051
Other	408	351
Less: Valuation allowance	(59)	(63)
Total deferred tax assets	2,864	3,030
Depreciation	(2,929)	(2,431)
Intangibles	(749)	(803)
Total deferred tax liabilities	(3,678)	(3,234)
Net deferred tax liability	(814)	(204)
United Airlines, Inc.
Deferred income tax asset (liability):
Federal and state net operating loss (NOL) carryforwards	372	574
Deferred revenue	1,232	1,090
Employee benefits, including pension, postretirement and medical	885	1,051
Other	406	351
Less: Valuation allowance	(59)	(63)
Total deferred tax assets	2,836	3,003
Depreciation	(2,929)	(2,431)
Intangibles	(749)	(803)
Total deferred tax liabilities	(3,678)	(3,234)
Net deferred tax liability	$ (842)	$ (231)

Pension and Other Postretirement 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, 2018	Dec. 31, 2017	Dec. 31, 2016
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligation	$ 4,448	$ 4,739
Change in projected benefit obligation:
Projected benefit obligation at beginning of year	5,852		$ 5,253
Service cost	228	195	112
Interest cost	217	220	200
Actuarial (gain) loss	(601)	525
Gross benefits paid and settlements	(292)	(366)
Other	(8)	25
Projected benefit obligation at end of year	5,396	5,852
Change in plan assets:
Fair value of plan assets at beginning of year	3,932		3,355
Actual (loss) return on plan assets	(215)	510
Employer contributions	413	419
Gross benefits paid and settlements	(292)	(366)
Other	(11)	14
Fair value of plan assets at end of year	3,827	3,932
Funded status—Net amount recognized	(1,569)	(1,920)
Amounts recognized in the consolidated balance sheets consist of:
Noncurrent asset	13	9
Current liability	(6)	(8)
Noncurrent liability	(1,576)	(1,921)
Total liability	(1,569)	(1,920)
Amounts recognized in accumulated other comprehensive loss consist of:
Net actuarial loss	(1,382)	(1,610)
Prior service cost	(5)	(1)
Total accumulated other comprehensive loss	(1,387)	(1,611)
Other Postretirement Benefits
Change in projected benefit obligation:
Projected benefit obligation at beginning of year	1,710		1,687
Service cost	12	13	19
Interest cost	61	66	86
Plan participants' contributions	68	68
Actuarial (gain) loss	(285)	40
Benefits paid	(181)	(178)
Other	6	14
Projected benefit obligation at end of year	1,391	1,710
Change in plan assets:
Fair value of plan assets at beginning of year	54		$ 55
Actual (loss) return on plan assets	1	1
Employer contributions	111	108
Plan participants' contributions	68	68
Benefits paid	(181)	(178)
Fair value of plan assets at end of year	53	54
Funded status—Net amount recognized	(1,338)	(1,656)
Amounts recognized in the consolidated balance sheets consist of:
Current liability	(43)	(54)
Noncurrent liability	(1,295)	(1,602)
Total liability	(1,338)	(1,656)
Amounts recognized in accumulated other comprehensive loss consist of:
Net actuarial loss	554	301
Prior service cost	170	208
Total accumulated other comprehensive loss	$ 724	$ 509

Pension and Other Postretirement Plans - Accumulated Benefit Obligation and Projected Benefit Obligation in Excess of Plan Assets (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Retirement Benefits [Abstract]
Projected benefit obligation	$ 5,196	$ 5,637
Accumulated benefit obligation	4,286	4,567
Fair value of plan assets	$ 3,614	$ 3,709

Pension and Other Postretirement Plans - Components of Net Periodic Benefit Cost (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Curtailment gain	$ 0	$ 0	$ (107)
Pension Benefits
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	228	195	112
Interest cost	217	220	200
Expected return on plan assets	(292)	(243)	(216)
Curtailment gain	0	0	0
Amortization of unrecognized actuarial (gain) loss	130	128	76
Amortization of prior service credits	0	0	0
Other	1	5	5
Net periodic benefit cost (credit)	284	305	177
Other Postretirement Benefits
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	12	13	19
Interest cost	61	66	86
Expected return on plan assets	(2)	(2)	(2)
Curtailment gain	0	0	(107)
Amortization of unrecognized actuarial (gain) loss	(32)	(33)	(19)
Amortization of prior service credits	(37)	(37)	(31)
Other	0	0	0
Net periodic benefit cost (credit)	$ 2	$ 7	$ (54)

Pension and Other Postretirement Plans - Assumptions Used for Benefit Plans (Details)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Pension Benefits
Assumptions used to determine benefit obligations
Discount rate	4.20%	3.65%
Rate of compensation increase	3.89%	3.89%
Assumptions used to determine net expense
Discount rate	3.65%	4.19%
Expected return on plan assets	7.31%	7.02%
Rate of compensation increase	3.89%	3.54%
Other Postretirement Benefits
Assumptions used to determine benefit obligations
Discount rate	4.30%	3.63%
Assumptions used to determine net expense
Discount rate	3.63%	4.07%
Expected return on plan assets	3.00%	3.00%
Health care cost trend rate assumed for next year	6.00%	6.25%
Rate to which the cost trend rate is assumed to decline (ultimate trend rate in 2023)	5.00%	5.00%

Pension and Other Postretirement Plans - Allocation of Plan Assets (Details) - United Airlines, Inc.	12 Months Ended
	Dec. 31, 2018
Equity securities
Defined Benefit Plan Disclosure [Line Items]
Expected long-term rate of return	9.50%
Equity securities \| Minimum
Defined Benefit Plan Disclosure [Line Items]
Percent of total	30.00%
Equity securities \| Maximum
Defined Benefit Plan Disclosure [Line Items]
Percent of total	45.00%
Fixed-income securities
Defined Benefit Plan Disclosure [Line Items]
Expected long-term rate of return	5.80%
Fixed-income securities \| Minimum
Defined Benefit Plan Disclosure [Line Items]
Percent of total	30.00%
Fixed-income securities \| Maximum
Defined Benefit Plan Disclosure [Line Items]
Percent of total	40.00%
Alternatives
Defined Benefit Plan Disclosure [Line Items]
Expected long-term rate of return	7.30%
Alternatives \| Minimum
Defined Benefit Plan Disclosure [Line Items]
Percent of total	10.00%
Alternatives \| Maximum
Defined Benefit Plan Disclosure [Line Items]
Percent of total	25.00%
Other
Defined Benefit Plan Disclosure [Line Items]
Expected long-term rate of return	7.80%
Other \| Minimum
Defined Benefit Plan Disclosure [Line Items]
Percent of total	0.00%
Other \| Maximum
Defined Benefit Plan Disclosure [Line Items]
Percent of total	10.00%

Pension and Other Postretirement Plans - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Effect on post retirement benefit obligation, 1% Decrease	$ 139
Effect on total service and interest cost, 1% Decrease	10
Profit sharing and payroll tax expense	$ 334	$ 349	$ 628
Minimum
Defined Benefit Plan Disclosure [Line Items]
Percentage of pre-tax earnings paid for profit sharing plan	5.00%
Maximum
Defined Benefit Plan Disclosure [Line Items]
Percentage of pre-tax earnings paid for profit sharing plan	20.00%
IAM National Pension Plan \| Multi-Employer Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Multi-employer plan contributions		$ 435
IAM National Pension Plan \| Multi-Employer Pension Plans \| Minimum
Defined Benefit Plan Disclosure [Line Items]
Percent of company's contribution to plan		5.00%
United Airlines, Inc.
Defined Benefit Plan Disclosure [Line Items]
Expense for defined contribution plans	$ 693	$ 656	$ 592
United Airlines, Inc. \| Minimum
Defined Benefit Plan Disclosure [Line Items]
Employer contribution percentage	1.00%
United Airlines, Inc. \| Maximum
Defined Benefit Plan Disclosure [Line Items]
Employer contribution percentage	16.00%
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Expected employer contributions to pension and postretirement plans	$ 318
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Expected employer contributions to pension and postretirement plans	$ 95
Other Postretirement Benefits \| Deposit Administration Fund
Defined Benefit Plan Disclosure [Line Items]
Percent of plan assets invested	100.00%

Pension and Other Postretirement Plans - Defined Benefit Plan Assets Measured at Fair Value Using Unobservable Inputs (Details) - Level 3 - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plan, Change in Fair Value of Plan Assets, Level 3 Reconciliation [Roll Forward]
Fair value of plan assets at beginning of year	$ 383	$ 287
Actual return (loss) on plan assets:
Sold during the year	10	7
Held at year end	(21)	16
Purchases, sales, issuances and settlements (net)	(22)	73
Fair value of plan assets at end of year	$ 350	$ 383

Pension and Other Postretirement Plans - Estimated Future Benefit Payments (Details) $ in Millions	Dec. 31, 2018 USD ($)
Other Postretirement— subsidy receipts
2019	$ 5
2020	6
2021	6
2022	6
2023	7
Years 2024-2028	38
Pension Benefits
Pension and Other Postretirement
2019	329
2020	327
2021	353
2022	367
2023	379
Years 2024-2028	2,022
Other Postretirement Benefits
Pension and Other Postretirement
2019	100
2020	104
2021	108
2022	111
2023	113
Years 2024-2028	$ 575

Pension and Other Postretirement Plans - Participation in the IAM National Pension Plan (Details) - IAM National Pension Plan - Multi-Employer Pension Plans - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Multiemployer Plans [Line Items]
EIN	516031295
Pension Plan Number	002
Pension Protection Act Zone Status	Green
FIP/RP Status Pending/Implemented	No
Surcharge Imposed	No
United Airlines, Inc.
Multiemployer Plans [Line Items]
United's Contributions	$ 50	$ 41	$ 40

Investments and Fair Value Measurements - Narrative (Details) - USD ($)
$ / shares in Units, $ in Millions

12 Months Ended

Dec. 31, 2018

Dec. 31, 2017

^[1]

Dec. 31, 2016

^[1]

Jan. 31, 2019

Nov. 29, 2018

Investment in equity securities

$ 2,552.0

$ 3,241.0

$ 2,768.0

Investments in securities accounted for under the equity method

$ 144.0

EETC

Asset-backed Securities | Minimum

2019

Asset-backed Securities | Maximum

1 year

16 years

Corporate Debt | Minimum

1 year

Corporate Debt | Maximum

3 years

CDARS | Maximum

U.S. Government and Other Securities | Minimum

1 year

1 year

Azul

Investment in equity securities

$ 138.0

Equity stake

2.00%

Azul | Preferred Stock

Equity stake

8.00%

Republic

ManaAir | Subsequent Event

19.00%

ExpressJet Airlines, Inc. | ManaAir | Subsequent Event

49.90%

100.00%

Champlain

40.00%

Fulcrum

Equity Securities Without Readily Determinable Fair Value, Ownership Interest

0.09

Carrying value of other investment

$ 48.0

Synergy

Number of shares that may be put to United (in shares)

Loan amount

$ 456.0

516,000,000

Number of ADRs that may be put to United (in shares)

64,500,000

Percentage of installment that may be paid in shares (up to)

25.00%

Annual interest rate

3.00%

Number of shares that may be purchased at United's option (up to) (in shares)

77,400,000.0

Shares subject to increase in value agreement (in shares)

438,600,000.0

Kingsland

Number of shares that may be put to United (in shares)

144,800,000.0

Number of ADRs that may be put to United (in shares)

18,100,000

Market price of common stock at fifth anniversary (in dollars per share)

$ 12

Aggregate maximum possible combined put payment and guarantee amount

$ 217.2

[1]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606). See Note 1 to the financial statements contained in Part II, Item 8 of this report for additional information.

Investments and Fair Value Measurements - Fair Value of Financial Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Enhanced equipment trust certificates (EETC)	$ 0	$ 0
Avianca Holdings S.A. (AVH) Derivative Assets	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 1 \| Asset-backed Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	0	0
Level 1 \| CDARS
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	0	0
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 \| Other Fixed Income Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	0	0
Level 1 \| Other Investments Measured At NAV
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	0	0
Equity securities	0	0
Enhanced equipment trust certificates (EETC)	0	0
Avianca Holdings S.A. (AVH) Derivative Assets	0	0
Level 2 \| Other Investments Measured At NAV
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	0	0
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	0	0
Restricted cash	0	0
Equity securities	0	0
Level 3 \| Corporate Debt
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 \| CDARS
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	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 \| Other Fixed Income Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	0	0
Level 3 \| Other Investments Measured At NAV
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	0	0
Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	1,694	1,482
Restricted cash	105	109
Equity securities	249	99
Enhanced equipment trust certificates (EETC)	18	22
Avianca Holdings S.A. (AVH) Derivative Assets	11	0
Fair Value, Measurements, Recurring \| Corporate Debt
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	1,023	958
Fair Value, Measurements, Recurring \| Asset-backed Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	746	753
Fair Value, Measurements, Recurring \| CDARS
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	75	120
Fair Value, Measurements, Recurring \| U.S. Government and Agency Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	108	113
Fair Value, Measurements, Recurring \| Other Fixed Income Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	116	188
Fair Value, Measurements, Recurring \| Other Investments Measured At NAV
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	188	184
Fair Value, Measurements, Recurring \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	1,694	1,482
Restricted cash	105	109
Equity securities	249	99
Fair Value, Measurements, Recurring \| Level 2 \| Corporate Debt
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	1,023	958
Fair Value, Measurements, Recurring \| Level 2 \| Asset-backed Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	746	753
Fair Value, Measurements, Recurring \| Level 2 \| CDARS
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	75	120
Fair Value, Measurements, Recurring \| Level 2 \| U.S. Government and Agency Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	108	113
Fair Value, Measurements, Recurring \| Level 2 \| Other Fixed Income Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	116	188
Fair Value, Measurements, Recurring \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Enhanced equipment trust certificates (EETC)	18	22
Avianca Holdings S.A. (AVH) Derivative Assets	$ 11	$ 0

Investments and Fair Value Measurements - Carrying Amounts and Estimated Fair Values of Financial Instruments (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Carrying Amount
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, carrying amount	$ 13,445	$ 13,268
Synergy Term Loan, carrying amount	478	0
Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	13,450	13,787
Synergy Term Loan, fair value	422	0
Fair Value \| Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	0	0
Synergy Term Loan, fair value	0	0
Fair Value \| Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	9,525	10,115
Synergy Term Loan, fair value	0	0
Fair Value \| Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	3,925	3,672
Synergy Term Loan, fair value	$ 422	$ 0

Debt - Summary of Long-Term Debt (Details) - USD ($)
$ in Millions

12 Months Ended

Dec. 31, 2018

Dec. 31, 2017

Sep. 30, 2017

Jan. 31, 2017

Less: current portion of long-term debt

$ (1,230)

$ (1,565)

^[1]

Long-term debt, net

12,215

11,703

^[1]

Less: current portion of long-term debt

(1,230)

(1,565)

^[2]

Long-term debt, net

12,215

11,703

^[2]

UAL and United

Less: unamortized debt discount, premiums and debt issuance costs

13,636

13,431

(191)

(163)

Less: current portion of long-term debt

(1,230)

(1,565)

Long-term debt, net

$ 12,215

11,703

6.375% Senior Notes due 2018

6.375%

6% Senior Notes due 2020

4.25% Senior Notes due 2022

6.00%

4.25% Senior Notes due 2022 | United Airlines, Inc.

4.25%

4.25%

5% Senior Notes due 2024

5% Senior Notes due 2024 | United Airlines, Inc.

5.00%

Secured Debt | Notes payable, fixed interest rates of 0.0% to 9.52% (weighted average rate of 4.18% as of December 31, 2018), payable through 2030 | United Airlines, Inc.

5.00%

$ 8,811

8,661

Weighted average rate

4.18%

Secured Debt | Notes payable, fixed interest rates of 0.0% to 9.52% (weighted average rate of 4.18% as of December 31, 2018), payable through 2030 | Minimum | United Airlines, Inc.

2030

Secured Debt | Notes payable, fixed interest rates of 0.0% to 9.52% (weighted average rate of 4.18% as of December 31, 2018), payable through 2030 | Maximum | United Airlines, Inc.

0.00%

Secured Debt | Notes payable, floating interest rates of the London interbank offered rate (LIBOR) plus 1.05% to 1.75%, payable through 2030 | United Airlines, Inc.

9.52%

Secured Debt | Notes payable, floating interest rates of the London interbank offered rate (LIBOR) plus 1.05% to 1.75%, payable through 2030 | Maximum | United Airlines, Inc.

$ 2,051

1,880

Secured Debt | Notes payable, floating interest rates of the London interbank offered rate (LIBOR) plus 1.05% to 1.75%, payable through 2030 | LIBOR | Minimum | United Airlines, Inc.

2030

Secured Debt | Notes payable, floating interest rates of the London interbank offered rate (LIBOR) plus 1.05% to 1.75%, payable through 2030 | LIBOR | Maximum | United Airlines, Inc.

1.05%

Secured Debt | Term loan, LIBOR plus 1.75%, or alternative rate based on certain market rates plus 0.75%, due 2024 | United Airlines, Inc.

1.75%

$ 1,474

1,489

Secured Debt | Term loan, LIBOR plus 1.75%, or alternative rate based on certain market rates plus 0.75%, due 2024 | LIBOR | United Airlines, Inc.

2024

Secured Debt | Term loan, LIBOR plus 1.75%, or alternative rate based on certain market rates plus 0.75%, due 2024 | Alternative Rate Based on Certain Market Interest Rates | United Airlines, Inc.

1.75%

Unsecured Debt | 6.375% Senior Notes due 2018

0.75%

$ 0

300

6.375%

Unsecured Debt | 6% Senior Notes due 2020

2018

$ 300

300

6.00%

Unsecured Debt | 4.25% Senior Notes due 2022 | United Airlines, Inc.

2020

$ 400

400

4.25%

Unsecured Debt | 5% Senior Notes due 2024 | United Airlines, Inc.

2022

$ 300

300

5.00%

Unsecured Debt | Other | United Airlines, Inc.

2024

$ 300

$ 101

[1]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606). See Note 1 to the financial statements contained in Part II, Item 8 of this report for additional information.
[2]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606). See Note 1 to the financial statements contained in Part II, Item 8 of this report for additional information.

Debt - Contractual Principal Payments under Outstanding Long-Term Debt Agreements (Details) - UAL and United - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
2019	$ 1,230
2020	1,310
2021	1,300
2022	1,653
2023	703
After 2023	7,440
Long-term debt	$ 13,636	$ 13,431

Debt - Narrative (Details) - USD ($)		1 Months Ended		12 Months Ended
Debt - Narrative (Details) - USD ($)	Mar. 29, 2017	Sep. 30, 2017	Jan. 31, 2017	Dec. 31, 2018
4.25% Senior Notes due 2022
Debt Instrument [Line Items]
Fixed interest rate				4.25%
5% Senior Notes due 2024
Debt Instrument [Line Items]
Fixed interest rate				5.00%
United Airlines, Inc.
Debt Instrument [Line Items]
Aggregate principal amount				$ 424,000,000
United Airlines, Inc. \| Pass-Through Certificates
Debt Instrument [Line Items]
Long term debt				8,800,000,000
United Airlines, Inc. \| 4.25% Senior Notes due 2022
Debt Instrument [Line Items]
Aggregate principal amount		$ 400,000,000
Debt instrument maturity date		Oct. 01, 2022
Fixed interest rate		4.25%
Notes repurchase price		101.00%
United Airlines, Inc. \| 5% Senior Notes due 2024
Debt Instrument [Line Items]
Aggregate principal amount			$ 300,000,000
Debt instrument maturity date			Feb. 01, 2024
Fixed interest rate			5.00%
Notes repurchase price			101.00%
United Airlines, Inc. \| Surety Bond
Debt Instrument [Line Items]
Credit facility outstanding amount				$ 418,000,000
Credit facility expiration year				2022
United Airlines, Inc. \| Letters of Credit \| Cash Collateralized Letters of Credit
Debt Instrument [Line Items]
Credit facility outstanding amount				$ 73,000,000
United Airlines, Inc. \| Secured Debt
Debt Instrument [Line Items]
Quarterly principal repayment amount	0.25%
United Airlines, Inc. \| Secured Debt \| Term Loan due April 1, 2024 \| LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate	1.75%
United Airlines, Inc. \| Secured Debt \| Term Loan due April 1, 2024 \| Alternative Rate Based on Certain Market Interest Rates
Debt Instrument [Line Items]
Basis spread on variable rate	0.75%
United Airlines, Inc. \| Secured Debt \| Term Loan due April 1, 2024
Debt Instrument [Line Items]
Aggregate principal amount	$ 1,500,000,000
Debt instrument maturity date	Apr. 01, 2024
United Airlines, Inc. \| Secured Debt \| Revolving Credit Facility Available for Drawing until April 1, 2022
Debt Instrument [Line Items]
Credit agreement	$ 2,000,000,000
Revolving credit facility available for drawing date	Apr. 01, 2022
United Airlines, Inc. \| Secured Debt \| Revolving Credit Facility
Debt Instrument [Line Items]
Commitment fee percentage				0.75%
Available under revolving credit facility				$ 2,000,000,000
United Airlines, Inc. \| Secured Debt \| Revolving Credit Facility \| LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate				2.25%
United Airlines, Inc. \| Secured Debt \| Revolving Credit Facility \| Alternative Rate Based on Certain Market Interest Rates
Debt Instrument [Line Items]
Basis spread on variable rate				1.25%

Debt - Details of Past Through Trusts (Details) - USD ($)

12 Months Ended

Dec. 31, 2018

Dec. 31, 2017

Dec. 31, 2016

Feb. 28, 2018

$ 1,740,000,000

$ 2,765,000,000

^[1]

$ 808,000,000

^[1]

EETC

$ 1,000,000,000.0

424,000,000

United Airlines, Inc. | EETC

1,740,000,000

$ 2,765,000,000

^[2]

$ 808,000,000

^[2]

2,174,000,000

1,161,000,000

Remaining proceeds from issuance of debt to be received in future periods

1,161,000,000

1,013,000,000

United Airlines, Inc. | AA | February 2019

$ 717,000,000

4.15%

$ 0

Remaining proceeds from issuance of debt to be received in future periods

717,000,000

United Airlines, Inc. | AA | February 2018

$ 677,000,000

3.50%

$ 677,000,000

Remaining proceeds from issuance of debt to be received in future periods

677,000,000

United Airlines, Inc. | A

$ 296,000,000

4.55%

$ 0

Remaining proceeds from issuance of debt to be received in future periods

296,000,000

United Airlines, Inc. | A | February 2018

$ 258,000,000

3.70%

$ 258,000,000

Remaining proceeds from issuance of debt to be received in future periods

258,000,000

United Airlines, Inc. | B | May 2018

$ 226,000,000

4.60%

$ 226,000,000

Remaining proceeds from issuance of debt to be received in future periods

226,000,000

$ 0

[1]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606). See Note 1 to the financial statements contained in Part II, Item 8 of this report for additional information.
[2]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606). See Note 1 to the financial statements contained in Part II, Item 8 of this report for additional information.

Debt - Summary of Collateral Covenants and Cross Default Provisions (Details) $ in Billions	12 Months Ended
	Dec. 31, 2018 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	160.00%
6.375% Senior Notes due 2018
Debt Instrument [Line Items]
Fixed interest rate	6.375%
Debt instrument maturity year	2018
6% Senior Notes due 2020
Debt Instrument [Line Items]
Fixed interest rate	6.00%
Debt instrument maturity year	2020
5% Senior Notes due 2024
Debt Instrument [Line Items]
Fixed interest rate	5.00%
Debt instrument maturity year	2024
4.25% Senior Notes due 2022
Debt Instrument [Line Items]
Fixed interest rate	4.25%
Debt instrument maturity year	2022

Leases and Capacity Purchase Agreements - Future Minimum Lease Payments under Operating and Capital Leases (Details) - USD ($)
$ in Millions

Dec. 31, 2018

Dec. 31, 2017

^[1]

Capital Leases

$ 308

170

147

123

104

1,268

Minimum lease payments

2,120

Imputed interest

(837)

Present value of minimum lease payments

1,283

Current portion

(149)

$ (128)

Long-term obligations under capital leases

1,134

$ 996

Airport Construction Projects

Operating Leases

Operating property and equipment under capital leases

886

Obligations under capital leases

920

Facility and Other Operating Leases

1,330

1,351

1,107

970

953

7,029

Minimum lease payments

12,740

Aircraft Operating Leases

845

682

583

407

379

1,160

Minimum lease payments

$ 4,056

[1]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606). See Note 1 to the financial statements contained in Part II, Item 8 of this report for additional information.

Leases and Capacity Purchase Agreements - Narrative (Details)
$ in Millions

12 Months Ended

Dec. 31, 2019

USD ($)

Dec. 31, 2018

USD ($)

Aircraft

Dec. 31, 2017

USD ($)

Dec. 31, 2016

USD ($)

Dec. 31, 2015

USD ($)

Regional capacity purchase expense

$ 2,601

$ 2,232

^[1]

$ 2,197

^[1]

Expenses

38,011

34,113

^[1]

32,214

^[1]

Capacity Purchase Agreements | Forecast

2,363

2,196

^[2]

Scheduled block hours increase (decrease) percentage

10.00%

Change in cash obligation

$ 160

Aircraft Operating Leases

Operating leases obligations

$ 4,056

Minimum | Aircraft Operating Leases

Operating lease expiration date

5 years

2019

Maximum | Aircraft Operating Leases

Operating lease expiration date

26 years

2029

Regional capacity purchase expense

Nonaircraft rent expense

$ 1,300

1,300

1,200

$ 2,601

2,232

^[3]

2,197

^[3]

Number of aircrafts under the extended term of contract | Aircraft

125

Capacity purchase agreement contract expiration date after extension

Dec. 31, 2022

Expenses

$ 38,009

34,111

^[3]

32,212

^[3]

United Airlines, Inc. | Capacity Purchase Agreements

$ 2,363

2,196

^[4]

Number of regional aircraft | Aircraft

559

Airline capacity purchase arrangements, expiration year

2029

United Airlines, Inc. | Revaluation of Liabilities

United Airlines, Inc. | Variable Interest Entity, Not Primary Beneficiary

Net accretion amounts

$ 60

$ 82

Operating leases obligations

1,300

United Airlines, Inc. | Regional Aircraft

Regional capacity purchase expense

$ 505

458

439

United Airlines, Inc. | Minimum

United Airlines, Inc. | Maximum

Imputed interest rate

3.50%

Remaining lease term

1 year

United Airlines, Inc. | Mainline

Imputed interest rate

115.10%

Remaining lease term

6 years

Number of assets subject to lease | Aircraft

United Airlines, Inc. | Regional Carrier

Number of assets subject to lease | Aircraft

United Airlines, Inc. | Regional Carrier | Capacity Purchase Agreements

Expenses

$ 979

907

$ 935

Accounts receivable from regional carriers

$ 0

CRJ 200 | United Airlines, Inc. | Maximum

Number of aircraft to operate | Aircraft

Chicago O'Hare | Airline Use and Lease Agreement - Chicago O'Hare

Chicago O'Hare | Minimum | Hangars, Ground Equipment Maintenance Building and Employee Parking Lease

15 years

Chicago O'Hare | Maximum | Hangars, Ground Equipment Maintenance Building and Employee Parking Lease

15 years

Termination of an engine maintenance service agreement

30 years

[1]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606) and Accounting Standards Update No. 2017-07, Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost. See Note 1 to the financial statements contained in Part II, Item 8 of this report for additional information.
[2]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606). See Note 1 to the financial statements contained in Part II, Item 8 of this report for additional information.
[3]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606) and Accounting Standards Update No. 2017-07, Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost. See Note 1 to the financial statements contained in Part II, Item 8 of this report for additional information.
[4]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606). See Note 1 to the financial statements contained in Part II, Item 8 of this report for additional information.

Leases and Capacity Purchase Agreements - Future Lease Payment under Terms of Capacity Purchase Agreement (Details) $ in Billions	Dec. 31, 2018 USD ($)
Leases [Abstract]
2019	$ 2.2
2020	2.0
2021	1.8
2022	1.4
2023	0.8
2024	3.1
Total	$ 11.3

Variable Interest Entities (Details)	Dec. 31, 2018 aircraft
Mainline
Variable Interest Entity [Line Items]
Aircraft under operating lease, fixed purchase options	23
Regional Carrier
Variable Interest Entity [Line Items]
Aircraft under operating lease	90

Commitments and Contingencies - Narrative (Details) $ / shares in Units, Employee in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($) Employee commitment aircraft Option Aircraft	Nov. 29, 2018 USD ($) $ / shares shares	Feb. 28, 2018 USD ($)
Commitments and Contingencies [Line Items]
Aggregate balance	$ 11,300,000,000
Number of call options to purchase regional jet aircraft \| Option	292
United Airlines, Inc.
Commitments and Contingencies [Line Items]
Debt instrument principal amount	$ 424,000,000
Number of employees \| Employee	92
Percentage of employees represented by various U.S. labor organizations	83.00%
Tax-Exempt Special Facilities Revenue Bonds
Commitments and Contingencies [Line Items]
Guarantor obligations, maximum exposure	$ 1,900,000,000.0
Operating leases obligations	1,300,000,000
Capital leases obligations	466,000,000
Tax-Exempt Special Facilities Revenue Bonds \| Indirect Guarantee of Indebtedness
Commitments and Contingencies [Line Items]
Guarantor obligations, maximum exposure	164,000,000
Contingent liabilities based on participation	1,700,000,000
Floating Rate Debt
Commitments and Contingencies [Line Items]
Debt instrument principal amount	3,500,000,000.0
Fixed Rate Debt
Commitments and Contingencies [Line Items]
Debt instrument principal amount	27,000,000
Loans And Leases From Non U S Entities
Commitments and Contingencies [Line Items]
Aggregate balance	3,200,000,000
Aircraft Mortgage Debt
Commitments and Contingencies [Line Items]
Guarantor obligations, maximum exposure	$ 145,000,000
Minimum \| Tax-Exempt Special Facilities Revenue Bonds
Commitments and Contingencies [Line Items]
Maturity date	2019
Minimum \| Tax-Exempt Special Facilities Revenue Bonds \| Indirect Guarantee of Indebtedness
Commitments and Contingencies [Line Items]
Maturity date	2022
Maximum
Commitments and Contingencies [Line Items]
Debt instrument, remaining terms	12 years
Maximum \| Tax-Exempt Special Facilities Revenue Bonds
Commitments and Contingencies [Line Items]
Maturity date	2038
Maximum \| Tax-Exempt Special Facilities Revenue Bonds \| Indirect Guarantee of Indebtedness
Commitments and Contingencies [Line Items]
Maturity date	2051
Maximum \| Loans And Leases From Non U S Entities
Commitments and Contingencies [Line Items]
Debt instrument, remaining terms	12 years
Kingsland
Commitments and Contingencies [Line Items]
Number of shares that may be put to United (in shares) \| shares		144,800,000.0
Number of ADRs that may be put to United (in shares) \| shares		18,100,000
Market price of common stock at fifth anniversary (in dollars per share) \| $ / shares		$ 12
Aggregate maximum possible combined put payment and guarantee amount		$ 217,200,000
Contingent liabilities based on participation		$ 31,000,000
EETC
Commitments and Contingencies [Line Items]
Debt instrument principal amount			$ 1,000,000,000.0
EETC \| United Airlines, Inc.
Commitments and Contingencies [Line Items]
Debt instrument principal amount	$ 2,174,000,000
Embraer E175
Commitments and Contingencies [Line Items]
Number of aircrafts expects to take delivery \| Aircraft	25
Number of firm commitments \| commitment	25
Boeing 737 MAX
Commitments and Contingencies [Line Items]
Number of aircrafts expects to take delivery \| Aircraft	20
Boeing 787
Commitments and Contingencies [Line Items]
Number of aircrafts expects to take delivery \| Aircraft	8
Boeing 777-300ER
Commitments and Contingencies [Line Items]
Number of aircraft expected to be delivered \| aircraft	2
Airbus A319s
Commitments and Contingencies [Line Items]
Number of firm commitments \| aircraft	20
Embraer ERJ 145
Commitments and Contingencies [Line Items]
Number of aircraft under lease \| aircraft	54

Commitments and Contingencies - Firm Commitments and Options to Purchase Aircraft (Details)	Dec. 31, 2018 commitment
Airbus A350
Long-term Purchase Commitment [Line Items]
Number aircraft under purchase agreements	45
Boeing 737 MAX
Long-term Purchase Commitment [Line Items]
Number aircraft under purchase agreements	175
Boeing 777-300ER
Long-term Purchase Commitment [Line Items]
Number aircraft under purchase agreements	4
Boeing 787
Long-term Purchase Commitment [Line Items]
Number aircraft under purchase agreements	24
Embraer E175
Long-term Purchase Commitment [Line Items]
Number aircraft under purchase agreements	25

Commitments and Contingencies - Summary of Commitments Related to the Acquisition of Aircraft (Details) $ in Billions	Dec. 31, 2018 USD ($)
Commitments and Contingencies Disclosure [Abstract]
2019	$ 4.2
2020	5.3
2021	3.5
2022	2.8
2023	1.9
After 2023	7.0
Total	$ 24.7

Special Charges - Components of Special Charges (Details) - USD ($)
$ in Millions

3 Months Ended

12 Months Ended

Dec. 31, 2018

Sep. 30, 2018

Jun. 30, 2018

Mar. 31, 2018

Dec. 31, 2017

Sep. 30, 2017

Jun. 30, 2017

Mar. 31, 2017

Dec. 31, 2018

Dec. 31, 2017

Dec. 31, 2016

Operating:

Impairment of assets

$ 232

$ 11

$ 111

$ 23

$ 10

$ 15

$ 0

$ 377

$ 25

$ 412

Severance and benefit costs

116

Cleveland airport lease restructuring

Labor agreement costs

171

(Gains) losses on sale of assets and other special charges

(2)

(3)

Total operating special charges

301

129

487

176

^[1]

745

^[1]

Postretirement curtailment gain

(107)

Gains on extinguishment of debt and other

(1)

Total operating and nonoperating special charges before income taxes

487

176

637

Nonoperating mark-to-market (MTM) losses on financial instruments

(56)

(29)

135

(45)

Total special charges and MTM (gains) losses on financial instruments

245

(12)

264

(5)

492

176

637

Income tax benefit

(55)

(59)

(11)

(18)

(16)

(18)

(110)

(63)

(229)

Income tax adjustments

(5)

(179)

(5)

(179)

180

Total operating special charges, net of income taxes and income tax adjustments

$ 185

$ (9)

$ 205

$ (4)

$ (159)

$ 32

$ 28

$ 33

$ 377

$ (66)

$ 588

[1]

Special Charges - Narrative (Details)	1 Months Ended	3 Months Ended								12 Months Ended
Special Charges - Narrative (Details)	May 31, 2018 USD ($)	Dec. 31, 2018 USD ($)	Sep. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Sep. 30, 2017 USD ($)	Jun. 30, 2017 USD ($)	Mar. 31, 2017 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($) Contract	Dec. 31, 2016 USD ($)	Dec. 31, 2014 USD ($)
Special Charges [Line Items]
Fair value adjustments related to aircraft purchased off lease, write-off of unexercised aircraft purchase options and other impairments										$ 66,000,000
Fair value adjustments related to aircraft purchased off lease, write-off of unexercised aircraft purchase options and other impairments, net of tax										51,000,000
Termination of an engine maintenance service agreement		$ 64,000,000	$ 0	$ 0	$ 0					64,000,000	$ 0	$ 0
Termination of an engine maintenance service agreement, net of tax										50,000,000
Severance and benefit costs		7,000,000	9,000,000	11,000,000	14,000,000	$ 15,000,000	$ 23,000,000	$ 41,000,000	$ 37,000,000	41,000,000	116,000,000	37,000,000
Gain on change in market value of equity investments										28,000,000
Gain on change in market value of equity investments, net of tax										22,000,000
Losses due to the change in fair value of derivatives										33,000,000
Losses due to the change in fair value of derivatives, net of tax										26,000,000
Impairment of assets		232,000,000	$ 11,000,000	$ 111,000,000	$ 23,000,000	$ 10,000,000	15,000,000	$ 0	0	377,000,000	25,000,000	412,000,000
Cleveland airport lease restructuring										0	0	74,000,000
Cleveland airport lease restructuring, net of taxes												47,000,000
Labor agreement costs										0	0	171,000,000
Curtailment gain recognition of prior service credit										0	0	107,000,000
Postretirement Medical Plan \| Flight Attendant Postretirement Medical Plan
Special Charges [Line Items]
Curtailment gain recognition of prior service credit												47,000,000
Curtailment gain recognition of prior service credit, net of tax												30,000,000
Newark Liberty International Airport
Special Charges [Line Items]
Impairment of indefinite-lived intangible assets											412,000,000
Impairment of indefinite-lived intangible assets, net of tax benefits											264,000,000
Voluntary Early Out Program
Special Charges [Line Items]
Severance and benefit costs												37,000,000
Severance and benefits costs, net of tax												24,000,000
Obsolete Spare Parts Inventory
Special Charges [Line Items]
Impairment of assets											10,000,000
Impairment of assets, net of tax											6,000,000
Maintenance Service Agreement
Special Charges [Line Items]
Intangible assets impairment charge							15,000,000
Intangible assets impairment charge, net of tax							$ 10,000,000
Management Reorganization Initiative
Special Charges [Line Items]
Severance and benefit costs											33,000,000
Severance and benefits costs, net of tax											21,000,000
International Brotherhood of Teamsters
Special Charges [Line Items]
Severance and benefit costs										22,000,000	83,000,000
Severance and benefits costs, net of tax										17,000,000	$ 53,000,000
International Brotherhood of Teamsters \| Maximum \| Voluntary Early Out Program
Special Charges [Line Items]
Severance payment per participant									$ 100,000				$ 100,000
Int'l Association of Machinists
Special Charges [Line Items]
Number of new contracts extended \| Contract											7
Service contract extended year											2021
Labor agreement costs												171,000,000
Labor agreement costs, net of tax												110,000,000
Curtailment gain recognition of prior service credit												60,000,000
Curtailment gain recognition of prior service credit, net of tax												$ 38,000,000
Management
Special Charges [Line Items]
Severance and benefit costs										19,000,000
Severance and benefits costs, net of tax										$ 15,000,000
Hong Kong Routes
Special Charges [Line Items]
Intangible assets impairment charge		206,000,000
Intangible assets impairment charge, net of tax		$ 160,000,000
Brazil Routes
Special Charges [Line Items]
Intangible assets impairment charge	$ 105,000,000
Intangible assets impairment charge, net of tax	$ 82,000,000

Special Charges - Activity Related to the Accruals for Severance and Medical Costs and Future Lease Payments (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Severance/ Benefit Costs
Schedule Of Accrual Activity [Line Items]
Balance	$ 37	$ 14	$ 27
Accrual and related adjustments	41	116	37
Payments	(53)	(93)	(50)
Balance	25	37	14
Permanently Grounded Aircraft
Schedule Of Accrual Activity [Line Items]
Balance	22	41	78
Accrual and related adjustments	(7)	(4)	(17)
Payments	(3)	(15)	(20)
Balance	$ 12	$ 22	$ 41

Selected Quarterly Financial Data (Unaudited) - Summary of Selected Quarterly FInancial Data (Unaudited) (Details) - USD ($)
$ / shares in Units, $ in Millions

3 Months Ended

12 Months Ended

Dec. 31, 2018

Sep. 30, 2018

Jun. 30, 2018

Mar. 31, 2018

Dec. 31, 2017

Sep. 30, 2017

Jun. 30, 2017

Mar. 31, 2017

Dec. 31, 2018

Dec. 31, 2017

^[1]

Dec. 31, 2016

^[1]

Quarterly Financial Information Disclosure [Abstract]

Operating revenue

$ 10,491

$ 11,003

$ 10,777

$ 9,032

$ 9,451

$ 9,899

$ 10,008

$ 8,426

$ 41,303

$ 37,784

$ 36,558

652

1,203

1,161

276

776

1,138

1,437

320

3,292

3,671

4,344

$ 462

$ 836

$ 684

$ 147

$ 579

$ 645

$ 821

$ 99

$ 2,129

$ 2,144

^[2],[3],[4]

$ 2,234

^[2],[3],[4]

$ 1.71

$ 3.07

$ 2.49

$ 0.52

$ 1.99

$ 2.15

$ 2.67

$ 0.32

$ 7.73

$ 7.08

$ 6.77

Termination of an engine maintenance service agreement

$ 1.70

$ 3.06

$ 2.48

$ 0.52

$ 1.98

$ 2.15

$ 2.67

$ 0.32

$ 7.70

$ 7.06

$ 6.76

[1]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606) and Accounting Standards Update No. 2017-07, Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost. See Note 1 to the financial statements contained in Part II, Item 8 of this report for additional information.
[2]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606). See Note 1 to the financial statements contained in Part II, Item 8 of this report for additional information.
[3]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606). See Note 1 to the financial statements contained in Part II, Item 8 of this report for additional information.
[4]	Amounts adjusted due to the adoption of Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606). See Note 1 to the financial statements contained in Part II, Item 8 of this report for additional information.

Selected Quarterly Financial Data (Unaudited) - Impact of Significant Items on Quarterly Results (Details) - USD ($)
$ in Millions

3 Months Ended

12 Months Ended

Dec. 31, 2018

Sep. 30, 2018

Jun. 30, 2018

Mar. 31, 2018

Dec. 31, 2017

Sep. 30, 2017

Jun. 30, 2017

Mar. 31, 2017

Dec. 31, 2018

Dec. 31, 2017

Dec. 31, 2016

Operating:

Impairment of assets

$ 232

$ 11

$ 111

$ 23

$ 10

$ 15

$ 0

$ 377

$ 25

$ 412

Severance and benefit costs

116

(Gains) losses on sale of assets and other special charges

(2)

(3)

Total operating special charges

301

129

487

176

^[1]

745

^[1]