Unrealized gains (losses) on investments, net Unrealized Gain (Loss) on Investments Statistical Measurement [Domain] Statistical Measurement [Domain] Cargo revenue Cargo revenue Cargo and Freight [Member] Expected return on plan assets Defined Benefit Plan, Expected Return (Loss) on Plan Assets Miles earned Frequent Flyer Mileage Miles Awarded in Period Frequent flyer mileage miles awarded in period. Restricted cash in Prepaid expenses and other Restricted cash in Prepaid expenses and other Restricted Cash, Current Award Timing Predetermined Award Timing Predetermined [Flag] Republic Airways Republic Airways Holdings Inc. [Member] Republic Airways Holdings Inc. [Member] Asset Class [Axis] Asset Class [Axis] Entity File Number Entity File Number Additional Capital Invested Additional Paid-in Capital [Member] Tabular List, Table Tabular List [Table Text Block] Frequent flyer deferred revenue Contract With Customer, Liability, Current, Frequent Flyer Contract With Customer, Liability, Current, Frequent Flyer Purchases of short-term and other investments Payments to Acquire Short-Term Investments Schedule of Carrying Values and Estimated Fair Values of Financial Instruments Fair Value, by Balance Sheet Grouping [Table Text Block] Aggregate principal amount of guarantee Guarantor Obligations, Maximum Exposure, Undiscounted Employee stock awards Share-Based Payment Arrangement [Member] Schedule of Commitments Unrecorded Unconditional Purchase Obligations Disclosure [Table Text Block] Trading Arrangements, by Individual Trading Arrangements, by Individual [Table] Measurement Basis [Axis] Measurement Basis [Axis] Earnings per share, basic (in dollars per share) Earnings Per Share, Basic Adjustment to Compensation: Adjustment to Compensation [Axis] Named Executive Officers, Footnote Named Executive Officers, Footnote [Text Block] SPECIAL CHARGES Business Combination, Integration, Restructuring, and Other Related Costs [Text Block] 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] REVENUE RECOGNITION Revenue from Contract with Customer [Text Block] Regional capacity purchase Airline, Capacity Purchase Arrangements Schedule of Stock by Class [Table] Stock, Class of Stock [Table] Total other comprehensive loss, net of tax Other comprehensive loss Other Comprehensive Income (Loss), Net of Tax Total nonoperating special charges and unrealized (gains) losses on investments, net Special Charges And Unrealized Losses (Gains) On Financial Instruments, Non-Operating, Before Tax Special Charges And Losses On Financial Instruments, Nonoperating, Before Tax 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[Text Block] Pay vs Performance Disclosure [Line Items] U.S. government and agency notes US Government Agencies Debt Securities [Member] Compensation and Retirement Disclosure [Abstract] Retirement Benefits [Abstract] Forgone Recovery due to Disqualification of Tax Benefits, Amount Forgone Recovery due to Disqualification of Tax Benefits, Amount Non-Rule 10b5-1 Arrangement Terminated Non-Rule 10b5-1 Arrangement Terminated [Flag] Income before income taxes Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Entity Shell Company Entity Shell Company Airline Destination [Domain] Airline Destination [Domain] Other Other Liabilities, Noncurrent Schedule of Long-term Debt Instruments [Table] Schedule of Long-Term Debt Instruments [Table] Proceeds from sale of property and equipment Proceeds from Sale of Property, Plant, and Equipment Statement of Stockholders' Equity [Abstract] Statement of Stockholders' Equity [Abstract] Statement of Cash Flows [Abstract] Statement of Cash Flows [Abstract] Company Selected Measure Amount Company Selected Measure Amount Award Timing MNPI Considered Award Timing MNPI Considered [Flag] Total comprehensive income, net Comprehensive Income (Loss), Net of Tax, Attributable to Parent Name Measure Name Secured Debt Secured Debt [Member] Current maturities of operating leases Operating Lease, Liability, Current Class of Stock [Line Items] Class of Stock [Line Items] Deferred income taxes Deferred Income Tax Liabilities, Net Document Fiscal Period Focus Document Fiscal Period Focus Proceeds from issuance of debt and other financial liabilities, net of discounts and fees Proceeds From Issuance Of Long-Term Debt, Net Proceeds From Issuance Of Long-Term Debt, Net Award Timing Method Award Timing Method [Text Block] Total operating and nonoperating special charges and unrealized (gains) losses on investments, net Special Charges (Credits) And Losses On Financial Instruments, Operating And Nonoperating, Before Tax Special Charges (Credits) And Losses On Financial Instruments, Operating And Nonoperating, Before Tax Award Type Award Type [Axis] Long-term debt, carrying amount Outstanding principal balance Total Long-Term Debt Legal Entity [Axis] Legal Entity [Axis] Total assets Assets Investment, Name [Domain] Investment, Name [Domain] Trading Symbol Trading Symbol Landing fees and other rent Landing Fees and Other Rentals Stock issued for share-based awards, net of shares withheld for tax (in shares) Shares Issued, Shares, Share-Based Payment Arrangement, after Forfeiture Stock issued for settlement of warrants Stock Issued During Period, Value, Conversion Of Convertible Securities, Net Of Adjustments To Additional Paid In Capital Stock Issued During Period, Value, Conversion Of Convertible Securities, Net Of Adjustments To Additional Paid In Capital Entity Address, City or Town Entity Address, City or Town Operating Activities: Operating Activities: Cash Provided by (Used in) Operating Activity, Including Discontinued Operation [Abstract] Non-PEO NEO Average Compensation Actually Paid Amount Non-PEO NEO Average Compensation Actually Paid Amount Last Six Months of 2025 Unrecorded Unconditional Purchase Obligation, to be Paid, Remainder of Fiscal Year Compensation Actually Paid vs. Other Measure Compensation Actually Paid vs. Other Measure [Text Block] Entity Emerging Growth Company Entity Emerging Growth Company 2028 Long-Term Debt, Maturity, Year Three Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Preferred Stock Purchase Rights Stock Warrants Warrant [Member] Right-of-use assets acquired or modified through operating leases Right-of-Use Asset Obtained in Exchange for Operating Lease Liability Change in Fair Value as of Vesting Date of Prior Year Equity Awards Vested in Covered Year Change in Fair Value as of Vesting Date of Prior Year Equity Awards Vested in Covered Year [Member] Level 2 Fair Value, Inputs, Level 2 [Member] Equity method investments Equity Method Investments Insider Trading Policies and Procedures Not Adopted Insider Trading Policies and Procedures Not Adopted [Text Block] (Gains) losses on sale of assets and other special charges Net gains on sale of assets and other special charges Gain (Loss) On Sale Of Other Assets And Other Miscellaneous Charges Amount of gain (loss) on sale of other assets and other miscellaneous charges. Common shares, outstanding (in shares) Balance beginning (in shares) Balance ending (in shares) Common Stock, Shares, Outstanding PEO PEO [Member] Schedule of Operating Revenue by Geographic Region Disaggregation of Revenue [Table Text Block] Proceeds from sale of short-term and other investments Proceeds from Sale, Maturity and Collection of Investments Stock issued for share-based awards, net of shares withheld for tax Shares Issued, Value, Share-Based Payment Arrangement, After Forfeiture, Net Of Adjustments To Additional Paid In Capital Shares Issued, Value, Share-Based Payment Arrangement, After Forfeiture, Net Of Adjustments To Additional Paid In Capital Interest income Investment Income, Interest Number of employees Entity Number of Employees Unrecorded Unconditional Purchase Obligation [Line Items] Unrecorded Unconditional Purchase Obligation [Line Items] 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] New Surviving Entity New Surviving Entity Between Mesa Air Group, Inc. And Republic Airways Holdings Inc. [Member] New Merged Entity Between Mesa Air Group, Inc. And Republic Airways Holdings Inc. 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[Member] Azul Linhas Aereas Brasileiras S.A. Contribution to defined benefit plans Defined Contribution Plan, Cost Fair Value [Table] Fair Value [Table] Fair Value [Table] Additional capital invested Additional Paid in Capital, Common Stock Entities [Table] Entities [Table] Frequent Flyer Deferred Revenue [Roll Forward] Movement In Contract With Customer Liability [Roll Forward] Movement In Contract With Customer Liability [Roll Forward] Entity [Domain] Entity [Domain] Net cash provided by (used in) investing activities Cash Provided by (Used in) Investing Activity, Including Discontinued Operation Aggregate Change in Present Value of Accumulated Benefit for All Pension Plans Reported in Summary Compensation Table Aggregate Change in Present Value of Accumulated Benefit for All Pension Plans Reported in Summary Compensation Table [Member] Document Fiscal Year Focus Document Fiscal Year Focus Basis of Presentation Basis of Accounting, Policy [Policy Text Block] Operating lease right-of-use assets Operating Lease, Right-of-Use Asset Forgone Recovery, Explanation of Impracticability Forgone Recovery, Explanation of Impracticability [Text Block] Payments of long-term debt, finance leases and other financial liabilities Repayments of Long-Term Debt Effective income tax rate Effective Income Tax Rate Reconciliation, Percent Entity Interactive Data Current Entity Interactive Data Current Carrying Amount Reported Value Measurement [Member] Ancillary Services Ancillary Services [Member] Passenger - Ancillary Fees [Member] Remaining term of debt Debt Instrument, Remaining Term Years remaining on debt instruments. Equity [Abstract] Equity [Abstract] 2028 Unrecorded Unconditional Purchase Obligation, to be Paid, Year Three 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] Disaggregation of Revenue [Table] Disaggregation of Revenue [Table] Current maturities of long-term debt, finance leases, and other financial liabilities Long-Term Debt and Lease Obligation, Current Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Ownership [Domain] Ownership [Domain] Schedule of Components of Net Periodic Benefit Cost Schedule of Net Benefit Costs [Table Text Block] Compensation Actually Paid vs. Total Shareholder Return Compensation Actually Paid vs. Total Shareholder Return [Text Block] ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) Comprehensive Income (Loss) Note [Text Block] Fair Value, Recurring and Nonrecurring [Table] Fair Value, Recurring and Nonrecurring [Table] United Airlines, Inc. United Air Lines Inc [Member] United Airlines, Inc. [Member] Balance beginning Balance ending AOCI before Tax, Attributable to Parent Impact of UAL share repurchase Stock Repurchased During Period, Value Schedule of Components of Accumulated Other Comprehensive Income (Loss), Net of Tax Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block] Capital expenditures, net of flight equipment purchase deposit returns Payments to Acquire Productive Assets Depreciation and amortization Depreciation, Depletion and Amortization Entity Central Index Key Entity Central Index Key PEO Name PEO Name Schedule of Contractual Principal Payments Schedule of Maturities of Long-Term Debt [Table Text Block] Prior Year End Fair Value of Equity Awards Granted in Any Prior Year that Fail to Meet Applicable Vesting Conditions During Covered Year Prior Year End Fair Value of Equity Awards Granted in Any Prior Year that Fail to Meet Applicable Vesting Conditions During Covered Year [Member] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Outstanding Aggregate Erroneous Compensation Amount Outstanding Aggregate Erroneous Compensation Amount Revolving Credit Facility Revolving Credit Facility [Member] Tax-Exempt Special Facilities Revenue Bonds Tax Exempt Bonds [Member] Tax Exempt Bonds [Member] Schedule of Defined Benefit Plans Disclosures [Table] Defined Benefit Plan [Table] Arrangement Duration Trading Arrangement Duration Commitments and Contingencies [Table] Commitments and Contingencies [Table] Commitments And Contingencies [Table] After 2029 Long-Term Debt, Maturity, After Year Four Long-Term Debt, Maturity, After Year Four Exercise Price Award Exercise Price Entity Filer Category Entity Filer Category Local Phone Number Local Phone Number Class of Stock [Domain] Class of Stock [Domain] Additional 402(v) Disclosure Additional 402(v) Disclosure [Text Block] Collaborative Arrangement and Arrangement Other than Collaborative [Domain] Collaborative Arrangement and Arrangement Other than Collaborative [Domain] Other, net Payment for (Proceeds from) Other Investing Activity Subsequent Event Type [Axis] Subsequent Event Type [Axis] ASSETS Assets [Abstract] Credit Facility [Axis] Credit Facility [Axis] Underlying Security Market Price Change Underlying Security Market Price Change, Percent Debt Instrument [Axis] Debt Instrument [Axis] Total operating and nonoperating special charges and unrealized (gains) losses on investments, net of income taxes Special Charges (Credits), Net of Income Tax Benefit Total special items in the period. Chase and Other Partner Agreements Chase And Other Partner Agreements [Member] Chase And Other Partner Agreements [Member] FAIR VALUE MEASUREMENTS, INVESTMENTS AND NOTES RECEIVABLE Fair Value Disclosures [Text Block] PENSION AND OTHER POSTRETIREMENT BENEFIT PLANS Retirement Benefits [Text Block] Credit Facility [Domain] Credit Facility [Domain] Stockholders' equity: Equity, Attributable to Parent [Abstract] 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] Entity Address, Address Line One Entity Address, Address Line One Repurchases of common stock Value of shares repurchased Treasury Stock, Value, Acquired, Cost Method Aircraft fuel, spare parts and supplies, net Aircraft fuel, spare parts and supplies, net Airline Related Inventory, Net Accumulated Other Comprehensive Income (Loss) Accumulated Other Comprehensive Income (Loss) AOCI Attributable to Parent [Member] Investment, Name [Axis] Investment, Name [Axis] Investments [Domain] Investments [Domain] Long-term obligations under operating leases Operating Lease, Liability, Noncurrent Stock issued for settlement of warrants (in shares) Stock Issued During Period, Shares, Conversion of Convertible Securities Ownership [Axis] Ownership [Axis] Unconditional Purchase Obligation, Category of Goods or Services Acquired [Domain] Unconditional Purchase Obligation, Category of Goods or Services Acquired [Domain] Amortization of prior service credit Defined Benefit Plan, Amortization of Prior Service Cost (Credit) Special charges Total operating special charges Restructuring, Settlement and Impairment Provisions Fair Value as of Grant Date Award Grant Date Fair Value Entity Registrant Name Entity Registrant Name Stock Price or TSR Estimation Method Stock Price or TSR Estimation Method [Text Block] Total Defined Benefit Plan, Net Periodic Benefit Cost (Credit) Champlain Enterprises LLC Champlain Enterprises LLC [Member] Champlain Enterprises LLC [Member] Salaries and related costs Labor and Related Expense Nonoperating debt extinguishment and modification fees Debt Extinguishment and Modification Fees, Non-Operating Debt Extinguishment and Modification Fees, Non-Operating Dilutive effect of employee stock awards (in shares) Incremental Common Shares Attributable to Dilutive Effect of Share-Based Payment Arrangements Total operating expense Costs and Expenses Investment interests received in exchange for loans, goods and services Other Significant Noncash Transaction, Value of Consideration Received Document Quarterly Report Document Quarterly Report Deferred income tax expense Deferred Income Taxes and Tax Credits Long-term debt, fair value Long-Term Debt, Fair Value Schedule of Fair Value Measurement Inputs and Valuation Techniques Fair Value Measurement Inputs and Valuation Techniques [Table Text Block] Changed Peer Group, Footnote Changed Peer Group, Footnote [Text Block] Investment carrying amount Equity Securities without Readily Determinable Fair Value, Amount Number of operating segments Number of Operating Segments MileagePlus Notes MileagePlus Senior Secured Notes [Member] MileagePlus Senior Secured Notes Pacific Pacific Destination [Member] Adjustment To PEO Compensation, Footnote Adjustment To PEO Compensation, Footnote [Text Block] Investment Type [Axis] Investment Type [Axis] Interest cost Defined Benefit Plan, Interest Cost Title Trading Arrangement, Individual Title Peer Group Total Shareholder Return Amount Peer Group Total Shareholder Return Amount Unrecorded Unconditional Purchase Obligation [Table] Unrecorded Unconditional Purchase Obligation [Table] Collaborative Arrangement and Arrangement Other than Collaborative [Axis] Collaborative Arrangement and Arrangement Other than Collaborative [Axis] Restatement Determination Date: Restatement Determination Date [Axis] Latin America Latin America Destination [Member] Non-PEO NEO Non-PEO NEO [Member] Accumulated Other Comprehensive Income (Loss) [Table] Accumulated Other Comprehensive Income (Loss) [Table] Schedule of Components of Special Charges Restructuring and Related Costs [Table Text Block] Other, net Proceeds from (Payment for) Other Financing Activity Accumulated Other Comprehensive Income (Loss) [Line Items] Accumulated Other Comprehensive Income (Loss) [Line Items] Name Trading Arrangement, Individual Name All Award Types Award Type [Domain] Equity Awards Adjustments Equity Awards Adjustments [Member] Pension Benefits Adjustments, Footnote Pension Benefits Adjustments, Footnote [Text Block] Disaggregation of Revenue [Line Items] Disaggregation of Revenue [Line Items] Defined Benefit Plan Disclosure [Line Items] Defined Benefit Plan Disclosure [Line Items] Compensation Amount Outstanding Recovery Compensation Amount Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] Statement of Comprehensive Income [Abstract] Statement of Comprehensive Income [Abstract] Certificates of deposit placed through an account registry service (CDARS) Certificates of Deposit [Member] Recovery of Erroneously Awarded Compensation Disclosure [Line Items] Fair Value Estimate of Fair Value Measurement [Member] Revenue recognized Contract with Customer, Liability, Revenue Recognized Retirement Plan Type [Domain] Retirement Plan Type [Domain] MNPI Disclosure Timed for Compensation Value MNPI Disclosure Timed for Compensation Value [Flag] Airline Destinations [Axis] Airline Destination [Axis] Name Awards Close in Time to MNPI Disclosures, Individual Name Equity interests exchanged for commitment to facilitate merger transaction Equity Ownership, Excluding Consolidated Entity and Equity Method Investee, Percentage Restricted cash in Investments in affiliates and other, net Restricted cash in Investments in affiliates and other, net Restricted Cash, Noncurrent Aggregate Erroneous Compensation Not Yet Determined Aggregate Erroneous Compensation Not Yet Determined [Text Block] Operating revenue: Operating revenue: Revenues [Abstract] Stock-settled share-based compensation APIC, Share-Based Payment Arrangement, Increase for Cost Recognition Accumulated other comprehensive income Accumulated Other Comprehensive Income (Loss), Net of Tax Long-term debt, finance leases, and other financial liabilities Long-Term Debt and Lease Obligation 2026 Long-Term Debt, Maturity, Year One Changes in value Other Comprehensive Income (Loss) before Reclassifications, Tax Available-for-sale securities remaining maturities Available-For-Sale Investments, Maturity Term Available-For-Sale Investments, Maturity Term Total noncurrent assets Assets, Noncurrent Undrawn and available amount under revolving credit facility Line of Credit Facility, Remaining Borrowing Capacity Aggregate Pension Adjustments Service Cost Aggregate Pension Adjustments Service Cost [Member] Fair Value Hierarchy and NAV [Domain] Fair Value Hierarchy and NAV [Domain] Number of shares purchased as a result of warrants exercised (in shares) Class of Warrant or Right, Number of Securities Called by Warrants or Rights Investments and Other AOCI, Accumulated Gain (Loss), Debt Securities, Available-for-Sale, Parent [Member] Company Selected Measure Name Company Selected Measure Name Fair Value Measurement [Domain] Fair Value Measurement [Domain] Income tax benefit, net of valuation allowance Income Tax Expense (Benefit) Special Charges Income tax expense (benefit) special charges. Preferred stock Preferred Stock, Value, Issued Aggregate Available Trading Arrangement, Securities Aggregate Available Amount Accounts payable Accounts Payable, Current Stock Appreciation Rights (SARs) Stock Appreciation Rights (SARs) [Member] All Executive Categories All Executive Categories [Member] Common stock at par, $0.01 par value; authorized 1,000,000,000 shares; outstanding 323,801,715 and 327,899,771 shares at June 30, 2025 and December 31, 2024, respectively Common stock at par, $0.01 par value; authorized 1,000 shares; issued and outstanding 1,000 shares at both June 30, 2025 and December 31, 2024 Common Stock, Value, Issued Short-term investments Short-Term Investments COMMITMENTS, CONTINGENCIES, AND GUARANTEES Commitments and Contingencies Disclosure [Text Block] Diluted weighted-average shares outstanding (in shares) Weighted Average Number of Shares Outstanding, Diluted Commitments and contingencies Commitments and Contingencies Non-GAAP Measure Description Non-GAAP Measure Description [Text Block] Nonoperating unrealized (gains) losses on investments, net Gain (Loss) On Financial Instruments, Non-Operating Gain (Loss) On Financial Instruments, Non-Operating Entity Small Business Entity Small Business Income Tax Disclosure [Abstract] Income Tax Disclosure [Abstract] Other operating expenses Other Cost and Expense, Operating DEBT Long-Term Debt [Text Block] Document Transition Report Document Transition Report Ownership stake Equity Method Investment, Ownership Percentage Underlying Securities Award Underlying Securities Amount Special charges ratification payment Labor contract ratification bonuses Special charge Labor Contract Ratification Bonus Labor Contract Ratification Bonus Equity Component [Domain] Equity Component [Domain] Document Period End Date Document Period End Date PEO Actually Paid Compensation Amount PEO Actually Paid Compensation Amount INCOME TAXES Income Tax Disclosure [Text Block] Aggregate balance Contractual Obligation Awards Close in Time to MNPI Disclosures, Table Awards Close in Time to MNPI Disclosures [Table Text Block] Revenue from Contract with Customer [Abstract] Revenue from Contract with Customer [Abstract] Scenario [Axis] Scenario [Axis] Pension and postretirement benefit liability Liability, Retirement and Postemployment Benefits Document Type Document Type Level 3 Fair Value, Inputs, Level 3 [Member] EARNINGS PER SHARE Earnings Per Share [Text Block] Name Outstanding Recovery, Individual Name Employee benefit plans Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, after Tax Product and Service [Axis] Product and Service [Axis] Total operating revenue Revenue from Contract with Customer, Excluding Assessed Tax Revenue From Contract With Customer [Table] Revenue From Contract With Customer [Table] Revenue From Contract With Customer [Table] [Table] All Individuals All Individuals [Member] Long-term Debt, Type [Domain] Long-Term Debt, Type [Domain] Fair Value Disclosures [Abstract] Fair Value Disclosures [Abstract] Name Forgone Recovery, Individual Name Total current assets Assets, Current 2029 Unrecorded Unconditional Purchase Obligation, to be Paid, Year Four Statistical Measurement [Axis] Statistical Measurement [Axis] 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] Before Tax AOCI Attributable To Parent, Before Tax [Roll Forward] AOCI Attributable To Parent, Before Tax [Roll Forward] Atlantic Atlantic Destination [Member] Aggregate Erroneous Compensation Amount Aggregate Erroneous Compensation Amount Peer Group Issuers, Footnote Peer Group Issuers, Footnote [Text Block] Earnings available to common stockholders Net Income (Loss) Available to Common Stockholders, Basic Entity Information [Line Items] Entity Information [Line Items] Erroneous Compensation Analysis Erroneous Compensation Analysis [Text Block] Investments and other Other Comprehensive Income, Investments and Other, Net of Tax Other Comprehensive Income, Investments and Other, Net of Tax Fair Value [Line Items] Fair Value [Line Items] Fair Value [Line Items] Balance beginning Balance ending AOCI Tax, Attributable to Parent Rule 10b5-1 Arrangement Terminated Rule 10b5-1 Arrangement Terminated [Flag] Level 1 Fair Value, Inputs, Level 1 [Member] Restricted cash — noncurrent Restricted Cash, Noncurrent, Fair Value Disclosure Restricted Cash Fair Value Disclosure Deferred Taxes AOCI Attributable To Parent, Tax [Roll Forward] AOCI Attributable To Parent, Tax [Roll Forward] Earnings per share, diluted (in dollars per share) Earnings Per Share, Diluted Erroneously Awarded Compensation Recovery Erroneously Awarded Compensation Recovery [Table] Title of 12(b) Security Title of 12(b) Security Investing and Financing Activities Not Affecting Cash: Investing and Financing Activities Not Affecting Cash: Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract] Total AOCI Attributable to Parent, Net of Tax [Roll Forward] Floating Rate Debt Floating Rate Debt [Member] Floating Rate Debt [Member] Earnings Per Share [Abstract] Earnings Per Share [Abstract] Total nonoperating expense, net Nonoperating Income (Expense) After 2029 Unrecorded Unconditional Purchase Obligation, To Be Paid, After Year Four Unrecorded Unconditional Purchase Obligation, To Be Paid, After Year Four Frequent flyer deferred revenue Contract With Customer, Liability, Noncurrent, Frequent Flyer Contract With Customer, Liability, Noncurrent, Frequent Flyer Other Stockholders' Equity, Other Repurchase of common stock (in shares) Number of shares repurchased (in shares) Treasury Stock, Shares, Acquired Scenario, Plan Scenario, Plan [Member] Award Timing Disclosures [Line Items] Service cost Defined Benefit Plan, Service Cost Measurement Frequency [Domain] Measurement Frequency [Domain] Accrued salaries and benefits Employee-related Liabilities, Current Carrying amount of loan receivable Financing Receivable, Excluding Accrued Interest, after Allowance for Credit Loss Net income Net income Net Income (Loss) Attributable to Parent Expiration Date Trading Arrangement Expiration Date Variable interest Variable Interest Entity, Qualitative or Quantitative Information, Ownership Percentage Gains on various aircraft sale-leaseback transactions Gain (Loss) On Aircraft Sale-Leaseback Transactions Gain (Loss) On Aircraft Sale-Leaseback Transactions Other fixed-income securities Fixed Income Securities [Member] Operating property and equipment, net Property, Plant and Equipment, Net Repurchases of common stock Payments for Repurchase of Common Stock Adoption Date Trading Arrangement Adoption Date 2026 Unrecorded Unconditional Purchase Obligation, to be Paid, Year One Compensation Actually Paid vs. Net Income Compensation Actually Paid vs. Net Income [Text Block] (Receivable from) Payable to Related Parties, Net Receivables from Stockholder [Member] Potential equity investments in connection with reorganization process Equity Securities, Restructuring Agreement, Maximum Investment Equity Securities, Restructuring Agreement, Maximum Investment Entity Current Reporting Status Entity Current Reporting Status Awards Close in Time to MNPI Disclosures Awards Close in Time to MNPI Disclosures [Table] Operating leases converted to finance leases Operating Leases Converted To Finance Leases Operating Leases Converted To Finance Leases Non-travel miles redeemed Non-Travel Miles Redemption, Frequent Flyer Deferred Revenue Non-travel miles redemption, frequent flyer deferred revenue. Operating income Operating Income (Loss) Retained earnings Retained Earnings (Accumulated Deficit) Commitments and Contingencies [Line Items] Commitments and Contingencies [Line Items] Commitments And Contingencies [Line Items] Statement of Financial Position [Abstract] Statement of Financial Position [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] Executive Category: Executive Category [Axis] Passenger revenue Passenger revenue Passenger [Member] Current Fiscal Year End Date Current Fiscal Year End Date Class of Stock [Axis] Class of Stock [Axis] Subsequent Event Type [Domain] Subsequent Event Type [Domain] Other Equity Investments Other Equity Investments [Member] Other Investments Aggregate Grant Date Fair Value of Equity Award Amounts Reported in Summary Compensation Table Aggregate Grant Date Fair Value of Equity Award Amounts Reported in Summary Compensation Table [Member] Mesa Mesa Air Group, Inc. [Member] Mesa Air Group, Inc. Retirement Plan Type [Axis] Retirement Plan Type [Axis] Miscellaneous, net Other Nonoperating Income (Expense) Statement [Table] Statement [Table] Restricted cash — current Restricted Cash, Current, Fair Value Disclosure Restricted Cash, Current, Fair Value Disclosure Financing Activities: Financing Activities: Cash Provided by (Used in) Financing Activity, Including Discontinued Operation [Abstract] Equity Awards Adjustments, Excluding Value Reported in Compensation Table Equity Awards Adjustments, Excluding Value Reported in the Compensation Table [Member] Percentage of employees represented by various U.S. labor organizations Percentage Of Employees Represented By Labor Organizations Percentage of employees represented by labor organizations Receivables, net Receivables, net Receivables, Net, Current Beginning Balance Ending Balance Contract with Customer, Liability Schedule of 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] Equity securities Equity Securities, FV-NI, Current Advance ticket sales Contract With Customer, Liability, Current, Advance Ticket Sales Contract With Customer, Liability, Current, Advance Ticket Sales Reconciliation of cash, cash equivalents and restricted cash: Cash and Cash Equivalents [Abstract] Number of aircraft operated Number of Aircraft Operated Property and equipment acquired through the issuance or modification of debt, finance leases and other financial liabilities Noncash Or Part Noncash Acquisition, Fixed Assets Acquired, Net Of Vendor Credits Noncash Or Part Noncash Acquisition, Fixed Assets Acquired, Net Of Vendor Credits Potentially dilutive securities (in shares) Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Total Unrecorded Unconditional Purchase Obligation All Adjustments to Compensation All Adjustments to Compensation [Member] Fair Value, by Balance Sheet Grouping [Table] Fair Value, by Balance Sheet Grouping [Table] Amendment Flag Amendment Flag 2027 Long-Term Debt, Maturity, Year Two Other Postretirement Benefits Other Postretirement Benefits Plan [Member] Revenue From Contract With Customer [Line Items] Revenue From Contract With Customer [Line Items] [Line Items] for Revenue From Contract With Customer [Table] [Table] Stock held in treasury, at cost Treasury Stock, Common, Value Termination Date Trading Arrangement Termination Date Net cash used in financing activities Cash Provided by (Used in) Financing Activity, Including Discontinued Operation Insider Trading Policies and Procedures Adopted Insider Trading Policies and Procedures Adopted [Flag] Measure: Measure [Axis] 2027 Unrecorded Unconditional Purchase Obligation, to be Paid, Year Two Basic weighted-average shares outstanding (in shares) Weighted Average Number of Shares Outstanding, Basic Distribution expenses Selling Expense Value of authorized shares yet to be purchased under program Share Repurchase Program, Remaining Authorized, Amount Schedule of Computation of Basic and Diluted Earnings Per Share Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Pay vs Performance Disclosure, Table Pay vs Performance [Table Text Block] Debt Disclosure [Abstract] Debt Disclosure [Abstract] Forgone Recovery due to Violation of Home Country Law, Amount Forgone Recovery due to Violation of Home Country Law, Amount Nonoperating income (expense): Nonoperating income (expense): Nonoperating Income (Expense) [Abstract] Entity Tax Identification Number Entity Tax Identification Number Scenario [Domain] Scenario [Domain] Operating expense: Operating expense: Costs and Expenses [Abstract] Amounts reclassified to earnings Reclassification from AOCI, Current Period, Tax Amounts reclassified to earnings Reclassification from AOCI, Current Period, before Tax, Attributable to Parent Unamortized debt discount Debt Instrument, Unamortized Discount Restructuring and Related Activities [Abstract] Restructuring and Related Activities [Abstract] Forgone Recovery due to Expense of Enforcement, Amount Forgone Recovery due to Expense of Enforcement, Amount Common stock, par value (in dollars per share) Common Stock, Par or Stated Value Per Share Advance Ticket Sales Advance Ticket Sales [Member] Advance Ticket Sales [Member] Common shares, issued (in shares) Common Stock, Shares, Issued 2029 Long-Term Debt, Maturity, Year Four CommuteAir CommuteAir LLC [Member] CommuteAir LLC [Member] UAL And United UAL And United [Member] UAL And United [Member] Interest expense Interest Expense, Nonoperating Trading Arrangement: Trading Arrangement [Axis] United Airlines Ventures Sustainable Flight Fund United Airlines Ventures Sustainable Flight Fund [Member] United Airlines Ventures Sustainable Flight Fund [Member] Total Shareholder Return Amount Total Shareholder Return Amount Aircraft rent Aircraft Rental Insider Trading Arrangements [Line Items] Security Exchange Name Security Exchange Name Last Six Months of 2025 Long-Term Debt, Maturity, Remainder of Fiscal Year Travel miles redeemed Travel Miles Redemption, Frequent Flyer Deferred Revenue Travel miles redemption, frequent flyer deferred revenue. Total noncurrent liabilities Liabilities, Noncurrent Other operating revenue Other Operating Revenue Product and Service, Other [Member] Purchase commitments Capital Addition Purchase Commitments [Member] Antidilutive Securities, Name [Domain] Antidilutive Securities, Name [Domain] Pension Adjustments Prior Service Cost Pension Adjustments Prior Service Cost [Member] Material Terms of Trading Arrangement Material Terms of Trading Arrangement [Text Block] Other Other Liabilities, Current Asset Class [Domain] Asset Class [Domain] Statement [Line Items] Statement [Line Items] Rule 10b5-1 Arrangement Adopted Rule 10b5-1 Arrangement Adopted [Flag] Cash and cash equivalents Cash and cash equivalents Cash and Cash Equivalent Common Stock Common Stock [Member] Entity Incorporation, State or Country Code Entity Incorporation, State or Country Code Non-NEOs Non-NEOs [Member] Corporate debt Corporate Debt Securities [Member] Net increase in cash, cash equivalents and restricted cash Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Period Increase (Decrease), Including Exchange Rate Effect and Discontinued Operation