737 MAX 8 Boeing 737 MAX 8 [Member] Boeing 737 MAX 8 Expected Aircraft Deliveries Number Of Aircrafts Expected To Take Delivery [Abstract] Number Of Aircrafts Expected To Take Delivery [Abstract] Statistical Measurement [Domain] Statistical Measurement [Domain] Payments of long-term debt, finance leases and other financing liabilities Repayments of long-term debt Prepayment of outstanding principal amount Repayments of Long-Term Debt Total miles awarded Frequent Flyer Mileage Miles Awarded in Period Frequent flyer mileage miles awarded in period. Cover [Abstract] Cover [Abstract] Republic Airways Holdings Inc. Republic Airways Holdings Inc. [Member] Republic Airways Holdings Inc. [Member] Net increase in cash, cash equivalents and restricted cash Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect Other Other Liabilities, Current Trading Symbol Trading Symbol Ownership stake Equity Method Investment, Ownership Percentage All Trading Arrangements All Trading Arrangements [Member] Frequent flyer deferred revenue Contract With Customer, Liability, Current, Frequent Flyer Contract With Customer, Liability, Current, Frequent Flyer Compensation Actually Paid vs. Net Income Compensation Actually Paid vs. Net Income [Text Block] Non-NEOs Non-NEOs [Member] Schedule of Computation of Basic and Diluted Earnings (Loss) Per Share Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Rule 10b5-1 Arrangement Adopted Rule 10b5-1 Arrangement Adopted [Flag] Awards Close in Time to MNPI Disclosures Awards Close in Time to MNPI Disclosures [Table] Receivables, allowance for credit losses Accounts Receivable, Allowance for Credit Loss, Current Equity method investments Equity Method Investments Pay vs Performance Disclosure [Line Items] Loans and Leases from Non-U.S. Entities Loans And Leases From Non U S Entities [Member] Loans And Leases From Non U.S Entities [Member] Peer Group Total Shareholder Return Amount Peer Group Total Shareholder Return Amount Non-Rule 10b5-1 Arrangement Adopted Non-Rule 10b5-1 Arrangement Adopted [Flag] Unrecorded Unconditional Purchase Obligation [Line Items] Unrecorded Unconditional Purchase Obligation [Line Items] FAIR VALUE MEASUREMENTS, INVESTMENTS AND NOTES RECEIVABLE Fair Value Disclosures [Text Block] Restructuring and Related Activities [Abstract] Restructuring and Related Activities [Abstract] Award Timing Disclosures [Line Items] Investment, Name [Domain] Investment, Name [Domain] Other Performance Measure, Amount Other Performance Measure, Amount Portion at Fair Value Measurement Portion at Fair Value Measurement [Member] Common shares, outstanding (in shares) Balance beginning (in shares) Balance ending (in shares) Common Stock, Shares, Outstanding Class of Warrant or Right [Axis] Class of Warrant or Right [Axis] Long-term obligations under operating leases Operating Lease, Liability, Noncurrent Other Other Operating Revenue Product and Service, Other [Member] Revenue from Contract with Customer [Abstract] Revenue from Contract with Customer [Abstract] Service cost Defined Benefit Plan, Service Cost Total other assets Other Assets, Noncurrent Entity Tax Identification Number Entity Tax Identification Number Total operating and nonoperating special charges and unrealized (gains) losses on investments, net of income taxes Special Items Net of Income Tax Benefit(s) Total special items in the period. Antidilutive Securities, Name [Domain] Antidilutive Securities, Name [Domain] Retirement Plan Type [Axis] Retirement Plan Type [Axis] Unrecorded Unconditional Purchase Obligation by Category of Item Purchased [Axis] Unrecorded Unconditional Purchase Obligation by Category of Item Purchased [Axis] Proposed extension period for technician labor contracts Technician Labor Contract, Proposed Extension Period Technician Labor Contract, Proposed Extension Period Net cash provided by operating activities Net Cash Provided by (Used in) Operating Activities COMBINED NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS (UNAUDITED) Unusual or Infrequent Items, or Both, Disclosure [Text Block] Treasury Stock Treasury Stock, Common [Member] Cash Flows from Operating Activities: Net Cash Provided by (Used in) Operating Activities [Abstract] Schedule of Components of Accumulated Other Comprehensive Income (Loss), Net of Tax Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block] Secured Debt Secured Debt [Member] Other Other Cost and Expense, Operating 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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to Parent Lease modifications and lease conversions Lease Modifications And Lease Conversions, Non-Cash Lease modifications that result in re-measurement of a lease and/or a change in lease classification Cash and cash equivalents Cash and Cash Equivalents, at Carrying Value Other, net Payments for (Proceeds from) Other Investing Activities Certificates of deposit placed through an account registry service (CDARS) Certificates of Deposit [Member] Year-over-Year Change in Fair Value of Equity Awards Granted in Prior Years That are Outstanding and Unvested Year-over-Year Change in Fair Value of Equity Awards Granted in Prior Years That are Outstanding and Unvested [Member] Amounts reclassified to earnings Reclassification from AOCI, Current Period, Tax Line of credit facility, increase (decrease) in maximum borrowing capacity Line Of Credit Facility, Increase (Decrease) In Maximum Borrowing Capacity Line Of Credit Facility, Increase (Decrease) In Maximum Borrowing Capacity Balance beginning Balance ending AOCI before Tax, Attributable to Parent Cash Flows from Financing Activities: Net Cash Provided by (Used in) Financing Activities [Abstract] Year-end Fair Value of Equity Awards Granted in Covered Year that are Outstanding and Unvested Year-end Fair Value of Equity Awards Granted in Covered Year that are Outstanding and Unvested [Member] Preferred stock Preferred Stock, Value, Issued Proceeds from sale of short-term and other investments Proceeds from Sale, Maturity and Collection of Investments Employee stock awards Share-Based Payment Arrangement [Member] Number of aircraft operated Number of Aircraft Operated Non-travel miles redeemed Non-Travel Miles Redemption, Frequent Flyer Deferred Revenue Non-travel miles redemption, frequent flyer deferred revenue. 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Earnings available to common stockholders Net Income (Loss) Available to Common Stockholders, Basic Compensation Actually Paid vs. Other Measure Compensation Actually Paid vs. Other Measure [Text Block] Total current liabilities Liabilities, Current Vesting Date Fair Value of Equity Awards Granted and Vested in Covered Year Vesting Date Fair Value of Equity Awards Granted and Vested in Covered Year [Member] Total assets Assets Aircraft rent Aircraft Rental CARES Act Loan Warrants CARES Act Loan Warrants [Member] CARES Act Loan Warrants Reconciliation of cash, cash equivalents and restricted cash: Cash and Cash Equivalents [Abstract] Other Other Liabilities, Noncurrent Forgone Recovery due to Violation of Home Country Law, Amount Forgone Recovery due to Violation of Home Country Law, Amount Restricted cash — current Restricted Cash, Current, Fair Value Disclosure Restricted Cash, Current, Fair Value Disclosure Commitments and contingencies Commitments and Contingencies Domestic (U.S. and Canada) Domestic Destination [Member] Termination Date Trading Arrangement Termination Date Percentage of employees represented by various U.S. labor organizations Percentage Of Employees Represented By Labor Organizations Percentage of employees represented by labor organizations Class of Warrant or Right [Domain] Class of Warrant or Right [Domain] Warrant exercise price (in dollars per share) Class of Warrant or Right, Exercise Price of Warrants or Rights Debt instrument, interest rate floor Debt Instrument, Interest Rate Floor Debt Instrument, Interest Rate Floor Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Advance ticket sales Contract With Customer, Liability, Current, Advance Ticket Sales Contract With Customer, Liability, Current, Advance Ticket Sales 2025 Long-Term Debt, Maturity, Year One Property and equipment acquired through the 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Performance [Table Text Block] Equity Awards Adjustments, Excluding Value Reported in Compensation Table Equity Awards Adjustments, Excluding Value Reported in the Compensation Table [Member] Operating property and equipment: Property, Plant and Equipment, Net [Abstract] Dividends or Other Earnings Paid on Equity Awards not Otherwise Reflected in Total Compensation for Covered Year Dividends or Other Earnings Paid on Equity Awards not Otherwise Reflected in Total Compensation for Covered Year [Member] Flight equipment Flight Equipment, Gross Entity File Number Entity File Number Term Loan Due 2021 Term Loan Due 2021 [Member] Term Loan Due 2021 REVENUE Revenue from Contract with Customer [Text Block] Document Fiscal Year Focus Document Fiscal Year Focus Last Six Months of 2024 Number Of Aircraft To Be Delivered Under the Contract, Remainder of Year Number Of Aircraft To Be Delivered Under the Contract, Remainder of Year Income Statement [Abstract] Income Statement [Abstract] Entity Address, Address Line One Entity Address, Address Line One Changes in value OCI, before Reclassifications, before Tax, Attributable to Parent Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] Warrants to purchase securities (in shares) Class Of Warrant or Right, Number Of Securities Called by Warrants Or Rights Issuable Under Agreement Class Of Warrant or Right, Number Of Securities Called by Warrants Or Rights Issuable Under Agreement Latin America Latin America Destination [Member] Aircraft fuel, spare, parts and supplies, obsolescence allowance Airline Related Inventory, Valuation Reserves Name Forgone Recovery, Individual Name Document Period End Date Document Period End Date Current maturities of finance leases Finance Lease, Liability, Current Investments in affiliates and other, less allowance for credit losses (2024 — $32; 2023 — $38) Investments in affiliates and other, less allowance for credit losses (2024 — $32; 2023 —$38) Financing Receivable, after Allowance for Credit Loss, Noncurrent Award Timing MNPI Considered Award Timing MNPI Considered [Flag] Advance Ticket Sales Advance Ticket Sales [Member] Advance Ticket Sales [Member] Line of Credit Facility, Lender [Domain] Line of Credit Facility, Lender [Domain] Asset Class [Axis] Asset Class [Axis] Insider Trading Arrangements [Line Items] 2025 Number Of Aircraft To Be Delivered Under the Contract, Year One Number Of Aircraft To Be Delivered Under the Contract, Year One Outstanding Aggregate Erroneous Compensation Amount Outstanding Aggregate Erroneous Compensation Amount CommuteAir LLC CommuteAir LLC [Member] CommuteAir LLC [Member] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] UAL And United UAL And United [Member] UAL And United [Member] Term Loan Facility Term Loan Facility [Member] Term Loan Facility Due PEO Actually Paid Compensation Amount PEO Actually Paid Compensation Amount Other Defined Benefit Plan, Other Cost (Credit) United Airlines Ventures Sustainable Flight Fund United Airlines Ventures Sustainable Flight Fund [Member] United Airlines Ventures Sustainable Flight Fund [Member] Revenue recognized Contract with Customer, Liability, Revenue Recognized Adjustment to Compensation: Adjustment to Compensation [Axis] Prepaid expenses and other Prepaid Expense and Other Assets, Current Document Transition Report Document Transition Report Document Quarterly Report Document Quarterly Report Ancillary Fees Passenger - Ancillary Fees [Member] Passenger - Ancillary Fees [Member] Travel miles redeemed Travel Miles Redemption, Frequent Flyer Deferred Revenue Travel miles redemption, frequent flyer deferred revenue. Fair Value, Recurring and Nonrecurring [Table] Fair Value, Recurring and Nonrecurring [Table] Accumulated other comprehensive loss Accumulated other comprehensive loss Accumulated Other Comprehensive Income (Loss), Net of Tax Entity Current Reporting Status Entity Current Reporting Status Retained Earnings Retained Earnings Retained Earnings [Member] Pension Adjustments Service Cost Pension Adjustments Service Cost [Member] Basic weighted-average shares outstanding (in shares) Weighted Average Number of Shares Outstanding, Basic Stock Price or TSR Estimation Method Stock Price or TSR Estimation Method [Text Block] Regional capacity purchase Airline, Capacity Purchase Arrangements Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Executive Category: Executive Category [Axis] Name Awards Close in Time to MNPI Disclosures, Individual Name Number of Firm Commitments Unrecorded Unconditional Purchase Obligation, Minimum Quantity Required Entity Filer Category Entity Filer Category Amounts reclassified to earnings Reclassification from AOCI, Current Period, Net of Tax, Attributable to Parent Company Selected Measure Name Company Selected Measure Name