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Property, Plant and Equipment [Table] Property, Plant and Equipment [Table] Total operating and nonoperating special charges (credits) and unrealized (gains) losses on investments, net of income taxes Special Items Net of Income Tax Benefit(s) Total special items in the period. Allocation of Plan Assets Schedule of Allocation of Plan Assets [Table Text Block] Trading Arrangements, by Individual Trading Arrangements, by Individual [Table] Level 3 Fair Value, Inputs, Level 3 [Member] 2024 Defined Benefit Plan, Expected Future Benefit Payment, Year One Proceeds from exercise of stock options Stock Issued During Period, Value, Stock Options Exercised Non-PEO NEO Average Compensation Actually Paid Amount Non-PEO NEO Average Compensation Actually Paid Amount Short-term investments Investments, Fair Value Disclosure Fulcrum BioEnergy, Inc., Boom, Alder Fuels LLC, Heart Aerospace Incorporated and ZeroAvia, Inc. Fulcrum BioEnergy, Inc., Boom, Alder Fuels LLC, Heart Aerospace Incorporated and ZeroAvia, Inc. [Member] Fulcrum BioEnergy, Inc., Boom, Alder Fuels LLC, Heart Aerospace Incorporated and ZeroAvia, Inc. 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United Air Lines Inc [Member] United Airlines, Inc. [Member] Agreement in principle pay rate increase period Agreement In Principle Pay Rate Increase Period Agreement In Pay Rate Principle Pay Rate Increase Period Aggregate principal amount Debt Instrument, Face Amount Current assets: Assets, Current [Abstract] Leases [Abstract] Leases [Abstract] After 2025 Number Of Aircraft To Be Delivered Under the Contract, After Year Two Number Of Aircraft To Be Delivered Under the Contract, After Year Two Entity Address, State or Province Entity Address, State or Province Compensation Actually Paid vs. Total Shareholder Return Compensation Actually Paid vs. Total Shareholder Return [Text Block] 100 basis points decrease in the weighted average discount rate Defined Benefit Plan, Effect Of 100 Basis Point Decrease In Discount Rate On Net Periodic Benefit Cost Defined Benefit Plan, Effect Of 100 Basis Point Decrease In Discount Rate On Net Periodic Benefit Cost Minimum lease payments Finance Lease, Liability, to be Paid PSP1 Warrants Payroll Support Program 1 (PSP1) Warrants [Member] Payroll Support Program 1 (PSP1) Warrants Class of Warrant or Right [Domain] Class of Warrant or Right [Domain] Accumulated Other Comprehensive Income (Loss) [Line Items] Accumulated Other Comprehensive Income (Loss) [Line Items] Asset Class [Domain] Asset Class [Domain] Airport slots Airport Slots And Gates Indefinite Lived [Member] Airport Slots And Gates [Member] Class of Stock [Domain] Class of Stock [Domain] China route authority China Route Authority [Member] China Route Authority Earnings (loss) available to common stockholders Net Income (Loss) Available to Common Stockholders, Basic Number of technicians Number of Technicians Number of Technicians PSP2 Note Payroll Support Program 2 (PSP2) Note [Member] Payroll Support Program 2 (PSP2) Note Present value of minimum lease payments Operating Lease, Liability Other liabilities and deferred credits: Deferred Credits and Other Liabilities [Abstract] Total Shareholder Return Vs Peer Group Total Shareholder Return Vs Peer Group [Text Block] Accumulated Other Comprehensive Income (Loss) AOCI Attributable to Parent [Member] Increase in prepaids and other assets Increase (Decrease) in Prepaid Expense and Other Assets Aggregate Erroneous Compensation Amount Aggregate Erroneous Compensation Amount Additions Charged to Costs and Expenses SEC Schedule, 12-09, Valuation Allowances and Reserves, Additions, Charge to Cost and Expense All Executive Categories All Executive Categories [Member] Other, net Effective Income Tax Rate Reconciliation, Other Adjustments, Amount Accumulated Other Comprehensive Income (Loss) [Table] Accumulated Other Comprehensive Income (Loss) [Table] Pension and Other Postretirement Liabilities Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member] Debt Disclosure [Abstract] Debt Disclosure [Abstract] Earnings Per Share [Abstract] Earnings Per Share [Abstract] Champlain Champlain Enterprises LLC [Member] Champlain Enterprises LLC [Member] Obsolescence allowance—spare parts: SEC Schedule, 12-09, Reserve, Inventory [Member] Common stock at par, $0.01 par value; authorized 1,000,000,000 shares; outstanding 328,018,739 and 326,930,321 shares at December 31, 2023 and 2022, respectively Common stock at par, $0.01 par value; authorized 1,000 shares; issued and outstanding 1,000 shares at December 31, 2023 and 2022 Common Stock, Value, Issued Total Unrecorded Unconditional Purchase Obligation Assets Measured at NAV Fair Value Measured at Net Asset Value Per Share [Member] Organization, Consolidation and Presentation of Financial Statements [Abstract] Organization, Consolidation and Presentation of Financial Statements [Abstract] Cash paid for amounts included in the measurement of lease liabilities: Cash Flow, Leases, Lessee [Abstract] Cash Flow, Leases, Lessee [Abstract] Financing cash flows for finance leases Finance Lease, Principal Payments Schedule of Defined Benefit Plans Disclosures [Table] Schedule of Defined Benefit Plans Disclosures [Table] Summary of Scheduled Future Minimum Lease Payments Under Finance Leases Finance Lease, Liability, to be Paid, Maturity [Table Text Block] Variable and short-term lease cost Variable And Short-Term Lease, Cost Variable And Short-Term Lease, Cost Airline Destination [Domain] Airline Destination [Domain] All Individuals All Individuals [Member] Miscellaneous, net Other Nonoperating Income (Expense) Entity Filer Category Entity Filer Category Alliances Alliances [Member] Alliances [Member] Non-PEO NEO Average Total Compensation Amount Non-PEO NEO Average Total Compensation Amount Statement [Table] Statement [Table] Current Fiscal Year End Date Current Fiscal Year End Date Defined Benefit Plan Assets Measured at Fair Value Using Unobservable Inputs Schedule of Effect of Significant Unobservable Inputs, Changes in Plan Assets [Table Text Block] Income Tax Provision (Benefit) Differed from Amounts Computed at the Statutory Federal Income Tax Rate and Significant Components Schedule of Effective Income Tax Rate Reconciliation [Table Text Block] Unrecognized tax benefits Unrecognized Tax Benefits Income Tax Authority [Axis] Income Tax Authority [Axis] PEO Name PEO Name Aircraft notes Used Aircraft Facility [Member] Used Aircraft Facility Fair Value, by Balance Sheet Grouping [Table] Fair Value, by Balance Sheet Grouping [Table] Preferred stock authorized to issue (in shares) Preferred Stock, Shares Authorized 2024 Contractual Obligation, to be Paid, Year One Restricted cash Restricted Cash, Current Years 2029 – 2033 Defined Benefit Plan, Expected Future Benefit Payment, after Year Five for Next Five Years Buildings Building [Member] Junior preferred stock outstanding (in shares) Preferred Stock, Shares Outstanding Non-Extending Lenders Non-Extending Lenders [Member] Non-Extending Lenders Deductions SEC Schedule, 12-09, Valuation Allowances and Reserves, Deduction Total other liabilities and deferred credits Other Liabilities And Deferred Credits, Noncurrent Other Liabilities And Deferred Credits, Noncurrent SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Table] SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Table] 787 Boeing 787 [Member] Boeing 787. Fixed interest rate Stated interest rate Debt Instrument, Interest Rate, Stated Percentage Initial term of operating leases Lessee, Operating And Finance Leases, Term Of Contract Lessee, Operating And Finance Leases, Term Of Contract Statement of Financial Position [Abstract] Statement of Financial Position [Abstract] Total stockholders' equity Balance Balance Equity, Attributable to Parent Schedule of Finite-Lived Intangible Assets [Table] Schedule of Finite-Lived Intangible Assets [Table] Sold during the year Defined Benefit Plan, Plan Assets Level 3 Reconciliation, Increase (Decrease) for Actual Return (Loss) on Plan Assets Sold Description of Fair Value of Financial Instruments and Fair Value Methodology Fair Value Measurement Inputs and Valuation Techniques [Table Text Block] Other Defined Benefit Plan, Other Cost (Credit) Finite-Lived Intangible Assets, Major Class Name [Domain] Finite-Lived Intangible Assets, Major Class Name [Domain] Pension and Other Postretirement Plan Assets Schedule of Defined Benefit Plans Disclosures [Table Text Block] Income (loss) before income taxes Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Fair Value Information Fair Value Measurement, Policy [Policy Text Block] Current liability Liability, Defined Benefit Plan, Current Level 2 Fair Value, Inputs, Level 2 [Member] 737 MAX 9 Boeing 737 MAX 9 [Member] Boeing 737 MAX 9 Income Taxes [Table] Income Taxes [Table] Income Taxes [Table] Capital expenditures, net of flight equipment purchase deposit returns Gross capital expenditures Payments to Acquire Productive Assets Income tax expense (benefit), net of valuation allowance Income Tax Expense (Benefit) Special Charges Income tax expense (benefit) special charges. Number of aircraft subject to operating leases Number Of Aircraft Subject To Operating Leases Number Of Aircraft Subject To Operating Leases Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Named Executive Officers, Footnote Named Executive Officers, Footnote [Text Block] Document Fiscal Period Focus Document Fiscal Period Focus Available under revolving credit facility Line of Credit Facility, Remaining Borrowing Capacity 2027 Lessee, Operating Lease, Liability, to be Paid, Year Four Employee stock awards Share-Based Payment Arrangement [Member] Nonoperating unrealized (gains) losses on investments, net Nonoperating unrealized gains (losses) Gain (Loss) On Financial Instruments, Non-Operating Gain (Loss) On Financial Instruments, Non-Operating City Area Code City Area Code Air Line Pilots Association Air Line Pilots Association [Member] Air Line Pilots Association EARNINGS (LOSS) PER SHARE Earnings Per Share [Text Block] Product and Service [Axis] Product and Service [Axis] Ownership stake Equity Method Investment, Ownership Percentage Flight equipment Flight Equipment, Gross Document Fiscal Year Focus Document Fiscal Year Focus Airbus A319 & Boeing 737-700 Airbus A319 & Boeing 737-700 [Member] Airbus A319 & Boeing 737-700 2033 Net Operating Loss Carry Forward Expiration Year 2033 [Member] Net Operating Loss Carry Forward Expiration Year 2033 Computer software Software and Software Development Costs [Member] Credit Agreement Credit Agreement [Member] Credit Agreement [Member] Labor contract ratification bonuses Labor Contract Ratification Bonus Labor Contract Ratification Bonus Exercise Price Award Exercise Price Finite-Lived Intangible Assets by Major Class [Axis] Finite-Lived Intangible Assets by Major Class [Axis] PSP3 Warrants Payroll Support Program 3 (PSP 3) Warrants [Member] Payroll Support Program 3 (PSP 3) Warrants Summary of Warrants Outstanding Schedule of Stockholders' Equity Note, Warrants or Rights [Table Text Block] Capital loss carryforwards, valuation allowance Capital Loss Carryforwards, Valuation Allowance Capital Loss Carryforwards, Valuation Allowance Financing Activities: Net Cash Provided by (Used in) Financing Activities, Continuing Operations [Abstract] Other operating revenue Other Operating Revenue Product and Service, Other [Member] Long-term Purchase Commitment [Line Items] Long-Term Purchase Commitment [Line Items] Income taxes Income Taxes Paid, Net Total liabilities and stockholders' equity Liabilities and Equity Summary of Commitments Unrecorded Unconditional Purchase Obligations Disclosure [Table Text Block] Total other assets Other Assets, Noncurrent Peer Group Total Shareholder Return Amount Peer Group Total Shareholder Return Amount Ownership [Domain] Ownership [Domain] Available for sale investment maturity term Available for Sale Investment Maturity Term Available for Sale Investment Maturity Term Nonoperating special termination benefits and settlement losses Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due To Settlement, Restructuring And Special And Contractual Termination Benefits Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due To Settlement, Restructuring And Special And Contractual Termination Benefits Operating lease right-of-use assets Operating Lease, Right-of-Use Asset Schedule of Long-term Debt Instruments [Table] Schedule of Long-Term Debt Instruments [Table] Equity Valuation Assumption Difference, Footnote Equity Valuation Assumption Difference, Footnote [Text Block] Liability Awards - RSUs Restricted Stock Units (RSUs) - Liability Awards [Member] Restricted Stock Units (RSUs) - Liability Awards [Member] Indefinite-lived Intangible Assets [Line Items] Indefinite-Lived Intangible Assets [Line Items] Discount rate Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate Arrangement Duration Trading Arrangement Duration Entity Address, City or Town Entity Address, City or Town Award Timing MNPI Considered Award Timing MNPI Considered [Flag] Special Charges [Line Items] Special Charges [Line Items] Special Charges [Line Items] Related Party Related Party [Member] Plan participants' contributions Defined Benefit Plan, Plan Assets, Contributions by Plan Participant Expenses Costs and Expenses, Related Party Deposit administration fund Deposit Administration Fund [Member] Deposit Administration Fund [Member] NOLs without an expiration date Deferred Tax Assets, Operating Loss Carryforwards, Not Subject to Expiration Ticket Taxes Ticket Taxes [Policy Text Block] Ticket Taxes Termination Date Trading Arrangement Termination Date Restricted cash - non-current Restricted Cash, Noncurrent, Fair Value Disclosure Restricted Cash Fair Value Disclosure Common shares, authorized (in shares) Common Stock, Shares Authorized Document Information [Table] Document Information [Table] Unusual or Infrequent Items, or Both [Abstract] Line of Credit Facility, Lender [Domain] Line of Credit Facility, Lender [Domain] Floating Rate Debt Floating Rate Debt [Member] Floating Rate Debt [Member] Indefinite-lived Intangible Assets [Axis] Indefinite-Lived Intangible Assets [Axis] Dilutive effect of stock warrants (in shares) Incremental Common Shares Attributable to Dilutive Effect of Call Options and Warrants Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities - Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Amounts reclassified to earnings, deferred taxes Reclassification from AOCI, Current Period, Tax Award Timing Disclosures [Line Items] Secured Overnight Financing Rate (SOFR) Secured Overnight Financing Rate (SOFR) [Member] Secured Overnight Financing Rate (SOFR) Additional issuance due to achievement of performance metrics Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Additional Issuance From Achievement of Performance Metrics Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Additional Issuance From Achievement of Performance Metrics Number of defined benefit pension plans Number of Defined Benefit Pension Plans Number of Defined Benefit Pension Plans 737 MAX 10 Boeing 737 MAX 10 [Member] Boeing 737 MAX 10 MileagePlus Term Loan Facility MileagePlus (MP) Term Loan Facility [Member] MileagePlus (MP) Term Loan Facility Fair value of RSUs and restricted stock vested in period Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Vested in Period, Fair Value Held at year end Defined Benefit Plan, Plan Assets Level 3 Reconciliation, Increase (Decrease) for Actual Return (Loss) on Plan Assets Still Held Document Information [Line Items] Document Information [Line Items] Restructuring Plan [Axis] Restructuring Plan [Axis] Firm Commitments and Options to Purchase Aircraft and Summary of Commitments Long-Term Purchase Commitment [Table Text Block] Rate to which the cost trend rate is assumed to decline (ultimate trend rate in 2033) Defined Benefit Plan, Ultimate Health Care Cost Trend Rate Surety Bonds Surety Bond [Member] Prepaid expenses and other Prepaid Expense and Other Assets, Current Amounts recognized in accumulated other comprehensive income (loss) consist of: Defined Benefit Plan, Amounts Recognized in Other Comprehensive Income (Loss) [Abstract] Projected amortization expense in 2026 Finite-Lived Intangible Asset, Expected Amortization, Year Three Insider Trading Arrangements [Line Items] AOCI Attributable to Parent, Net of Tax [Roll Forward] AOCI Attributable to Parent, Net of Tax [Roll Forward] Related Party, Type [Axis] Related Party, Type [Axis] Stock issued for share-based awards, net of shares withheld for tax (in shares) Shares Issued, Shares, Share-Based Payment Arrangement, after Forfeiture Entity Registrant Name Entity Registrant Name Material Terms of Trading Arrangement Material Terms of Trading Arrangement [Text Block] Award Timing Method Award Timing Method [Text Block] Number of employees electing to voluntarily separate from the company Restructuring And Related Cost, Number Of Employees Voluntarily Separated Restructuring And Related Cost, Number Of Employees Voluntarily Separated Projected amortization expense in 2025 Finite-Lived Intangible Asset, Expected Amortization, Year Two Summary of Unearned Compensation and Weighted-Average Remaining Period to Recognize Costs Share-Based Payment Arrangement, Nonvested Award, Cost [Table Text Block] Adjustment to Compensation, Amount Adjustment to Compensation Amount Payroll Support Program 2 & 3 (PSP 2 & 3) Warrants Payroll Support Program 2 & 3 (PSP 2 & 3) Warrants [Member] Payroll Support Program 2 & 3 (PSP 2 & 3) Warrants Employee Separation Employee Severance [Member] Expiration period for refundable tickets Refundable Tickets, Expiration Period Refundable Tickets, Expiration Period SPECIAL CHARGES (CREDITS) Business Acquisition, Integration, Restructuring and Other Related Costs [Text Block] Change in borrowing capacity Line Of Credit Facility, Increase (Decrease) In Maximum Borrowing Capacity Line Of Credit Facility, Increase (Decrease) In Maximum Borrowing Capacity Auditor Name Auditor Name Compensation Actually Paid vs. Net Income Compensation Actually Paid vs. Net Income [Text Block] Peer Group Issuers, Footnote Peer Group Issuers, Footnote [Text Block] Financial Assets and Liabilities Measured at Fair Value on Recurring Basis Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block] Payments of long-term debt, finance leases and other financial liabilities Debt prepayment Repayments of Long-Term Debt Entity Central Index Key Entity Central Index Key Amortization of debt discount and debt issuance costs Amortization of Debt Issuance Costs and Discounts Non-travel miles redeemed Non-Travel Miles Redemption, Frequent Flyer Deferred Revenue Non-travel miles redemption, frequent flyer deferred revenue. Compensation cost Share-Based Payment Arrangement, Expense Non-Rule 10b5-1 Arrangement Terminated Non-Rule 10b5-1 Arrangement Terminated [Flag] Gross Carrying Amount Finite-Lived Intangible Assets, Gross Commitments and Contingencies [Line Items] Commitments and Contingencies [Line Items] Commitments And Contingencies [Line Items] Income Tax Authority [Domain] Income Tax Authority [Domain] Purchases, sales, issuances and settlements (net) Defined Benefit Plan, Plan Assets Level 3 Reconciliation, Increase (Decrease) for Purchase, Sale, and Settlement Accrued salaries and benefits Employee-related Liabilities, Current After 2028 Unrecorded Unconditional Purchase Obligation, to be Paid, after Year Five Name Trading Arrangement, Individual Name Operating Revenue by Principal Geographic Region Disaggregation of Revenue [Table Text Block] Indirect Guarantee of Indebtedness Indirect Guarantee of Indebtedness [Member] Issuance of common stock Impact of UAL common stock issuance Stock Issued During Period, Value, New Issues Total operating revenue Revenue Revenue from Contract with Customer, Excluding Assessed Tax Mesa Mesa Air Group, Inc. [Member] Mesa Air Group, Inc. Entity [Domain] Entity [Domain] Long-term Debt, Type [Axis] Long-Term Debt, Type [Axis] Amendment Flag Amendment Flag Legal Entity [Axis] Legal Entity [Axis] Expenses associated with AIP Labor Contract Ratification, AIP Expense Labor Contract Ratification Weighted-average discount rate - operating leases Operating Lease, Weighted Average Discount Rate, Percent SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward] SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward] Interest Interest Paid, Excluding Capitalized Interest, Operating Activities Interest rate floor Debt Instrument, Interest Rate Floor Debt Instrument, Interest Rate Floor Investment interests received in exchange for goods and services Other Significant Noncash Transaction, Value of Consideration Received Other financial liabilities Deferred Tax Assets, Other Financial Liability Deferred Tax Assets, Other Financial Liability Long-term debt Long-term debt, net Long-Term Debt, Excluding Current Maturities Weighted-average remaining lease term - finance leases Finance Lease, Weighted Average Remaining Lease Term Actual income (loss) on plan assets Defined Benefit Plan, Plan Assets, Increase (Decrease) for Actual Return (Loss) Net deferred tax liability Deferred Tax Liabilities, Net Diluted weighted-average shares outstanding (in shares) Weighted Average Number of Shares Outstanding, Diluted Forgone Recovery, Explanation of Impracticability Forgone Recovery, Explanation of Impracticability [Text Block] Special termination benefits Special termination benefits - Voluntary Programs Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due To Special And Contractual Termination Benefits Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due To Special And Contractual Termination Benefits Carrying value of computer software Capitalized Computer Software, Gross Operating: Operating Expenses [Abstract] Company Selected Measure Amount Company Selected Measure Amount Airline Destinations [Axis] Airline Destinations [Axis] 2021 Term Loans Term Loan Due 2021 [Member] Term Loan Due 2021 2027 Defined Benefit Plan, Expected Future Benefit Payment, Year Four Total assets Assets Name Awards Close in Time to MNPI Disclosures, Individual Name After 2028 Finance Lease, Liability, to be Paid, after Year Five Additional leases that have not yet commenced Lessee, Operating And Finance Lease, Not Yet Commenced, Amount Lessee, Operating And Finance Lease, Not Yet Commenced, Amount Proceeds from issuance of warrants Proceeds from Issuance of Warrants Labor Costs Labor Costs [Policy Text Block] Labor Costs Policy Stock-settled share-based compensation APIC, Share-Based Payment Arrangement, Increase for Cost Recognition 2028 Long-Term Debt, Maturity, Year Five Salaries and related costs Labor and Related Expense Summary of Collateral Covenants and Cross Default Provisions Schedule of Financial Covenants [Table Text Block] Schedule of Financial Covenants Restructuring and Related Activities [Abstract] Restructuring and Related Activities [Abstract] Operating cash flows for finance leases Finance Lease, Interest Payment on Liability Aircraft fuel, spare parts and supplies, obsolescence allowance Airline Related Inventory, Valuation Reserves Vested (in dollars per share) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value Non-NEOs Non-NEOs [Member] Actual income (loss) on plan assets: Defined Benefit Plan, Plan Assets Level 3 Reconciliation, Increase (Decrease) for Purchase, Sale, and Settlement [Abstract] 2024 Number Of Aircraft To Be Delivered Under the Contract, Year One Number Of Aircraft To Be Delivered Under the Contract, Year One Defined Benefit Plan, Plan Assets, Category [Domain] Defined Benefit Plan, Plan Assets, Category [Domain] Pension Benefits Pension Pension Plan [Member] Audit Information [Abstract] Audit Information Term Loan Facility Term Loan Facility [Member] Term Loan Facility Due Non-PEO NEO Non-PEO NEO [Member] Loss contingency contract disputes Loss Contingency, Contract Disputes Loss Contingency, Contract Disputes  Percent of Total Defined Benefit Plan, Plan Assets, Target Allocation, Percentage Adjustment to Compensation: Adjustment to Compensation [Axis] UAV Fund United Airlines Ventures Sustainable Flight Fund [Member] United Airlines Ventures Sustainable Flight Fund [Member] Debt Instrument [Line Items] Debt Instrument [Line Items] Scenario [Axis] Scenario [Axis] Federal and state net operating loss ("NOL") carryforwards Deferred Tax Assets, Operating Loss Carryforwards Basic weighted-average shares outstanding (in shares) Weighted Average Number of Shares Outstanding, Basic Defined Benefit Plan, Change in Fair Value of Plan Assets, Level 3 Reconciliation [Roll Forward] Defined Benefit Plan, Change in Fair Value of Plan Assets, Level 3 Reconciliation [Roll Forward] Travel miles redeemed Travel Miles Redemption, Frequent Flyer Deferred Revenue Travel miles redemption, frequent flyer deferred revenue. Depreciation Deferred Tax Liabilities, Property, Plant and Equipment Schedule of Indefinite-Lived Intangible Assets [Table] Schedule of Indefinite-Lived Intangible Assets [Table] Operating revenue: Revenues [Abstract] 2025 Contractual Obligation, to be Paid, Year Two Voluntary Separation Leave Programs Voluntary Separation Leave (VSL) Programs [Member] Voluntary Separation Leave (VSL) Programs Changes in operating assets and liabilities - Increase (Decrease) in Other Operating Assets and Liabilities, Net [Abstract] Pay vs Performance Disclosure Pay vs Performance Disclosure [Table] Operating Activities: Net Cash Provided by (Used in) Operating Activities, Continuing Operations [Abstract] Statement [Line Items] Statement [Line Items] Intangibles Deferred Tax Liabilities, Intangible Assets Aircraft seats Aircraft Seats [Member] Aircraft Seats [Member]