Employee Classification [Axis] Employee Classification [Axis] Employee Classification Boeing 737 MAX 8 Boeing 737 MAX 8 [Member] Boeing 737 MAX 8 Investments and Other AOCI, Accumulated Gain (Loss), Debt Securities, Available-for-sale, Parent [Member] Scheduled Aircraft Deliveries Number Of Aircrafts Expected To Take Delivery [Abstract] Number Of Aircrafts Expected To Take Delivery [Abstract] Fair Value Hierarchy and NAV [Domain] Fair Value Hierarchy and NAV [Domain] Net loss Net loss Net Income (Loss) Attributable to Parent Total miles awarded Frequent Flyer Mileage Miles Awarded in Period Frequent flyer mileage miles awarded in period. Entity Emerging Growth Company Entity Emerging Growth Company Operating lease right-of-use assets Operating Lease, Right-of-Use Asset Unrecorded Unconditional Purchase Obligation [Table] Unrecorded Unconditional Purchase Obligation [Table] PSP1 Note Payroll Support Program 1 (PSP1) Note [Member] Payroll Support Program (PSP) Note [Member] Interest cost Defined Benefit Plan, Interest Cost Accrued salaries and benefits Employee-related Liabilities, Current Percent of capacity cut Unusual Or Infrequent Items, Percent Of Capacity Cut Unusual Or Infrequent Items, Percent Of Capacity Cut Statistical Measurement [Domain] Statistical Measurement [Domain] Intangibles - accumulated amortization Finite-Lived Intangible Assets, Accumulated Amortization Entity Address, Address Line One Entity Address, Address Line One Contractual Principal Payments under Long-Term Debt Agreements Schedule of Maturities of Long-term Debt [Table Text Block] Frequent flyer deferred revenue Contract With Customer, Liability, Current, Frequent Flyer Contract With Customer, Liability, Current, Frequent Flyer Equity securities Carrying value of investment Equity Securities, FV-NI, Current Revenue from Contract with Customer [Abstract] Revenue from Contract with Customer [Abstract] Roll Forward of Frequent Flyer Deferred Revenue Contract with Customer, Contract Asset, Contract Liability, and Receivable [Table Text Block] Additional capital invested Additional Paid in Capital, Common Stock Entity Filer Category Entity Filer Category Impairment of intangible assets Impairment of Intangible Assets (Excluding Goodwill) Restructuring Type [Axis] Restructuring Type [Axis] 2021 ATM Offering 2021 ATM Offering [Member] 2021 ATM Offering Kingsland Kingsland Holdings Limited [Member] Kingsland Holdings Limited [Member] Total other assets Other Assets, Noncurrent Property and equipment acquired through the issuance of debt, finance leases and other Noncash or Part Noncash Acquisition, Fixed Assets Acquired 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] Investment, Name [Axis] Investment, Name [Axis] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Debt Instrument, Interest Rate Period [Axis] Debt Instrument, Interest Rate Period [Axis] Debt Instrument, Interest Rate Period [Axis] Expected return on plan assets Defined Benefit Plan, Expected Return (Loss) on Plan Assets Interest rate floor Debt Instrument, Variable Rate Floor Debt Instrument, Variable Rate Floor Compensation and Retirement Disclosure [Abstract] Retirement Benefits [Abstract] 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 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 Severance and benefit costs Postemployment Benefits, Period Expense Avianca Holdings S.A. (“AVH”) Avianca Holdings S.A. (“AVH”) [Member] Avianca Holdings S.A. 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SOFR Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member] Total operating property and equipment Property, Plant, and Equipment and Finance Lease Right-of-Use Asset, before Accumulated Depreciation and Amortization Award Type [Domain] Award Type [Domain] Credit Facility [Domain] Credit Facility [Domain] ASSETS Assets [Abstract] 2024 Long-Term Debt, Maturity, Year Three Amortization of unrecognized (gain) loss Defined Benefit Plan, Amortization of Gain (Loss) Awards granted (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period Class of Financing Receivable [Domain] Class of Financing Receivable [Domain] Preferred stock Preferred Stock, Value, Issued Other Defined Benefit Plan, Other Cost (Credit) Airline Destinations [Axis] Airline Destinations [Axis] Entity Address, City or Town Entity Address, City or Town Sale price (in dollars per share) Shares Issued, Price Per Share Retained Earnings Retained Earnings [Member] Debt Instrument [Axis] Debt Instrument [Axis] COMBINED NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS (UNAUDITED) Unusual or Infrequent Items, or Both, Disclosure [Text Block] COMMITMENTS AND CONTINGENCIES Commitments and Contingencies Disclosure [Text Block] 2026 Notes Senior Secured Notes Due 2026 [Member] Senior Secured Notes Due 2026 Balance Balance AOCI Tax, Attributable to Parent Cash collateral for a standby letter of credit Cash Collateral for Borrowed Securities Amortization of prior service credit Defined Benefit Plan, Amortization of Prior Service Cost (Credit) Secured Debt Secured Debt [Member] Issuance price as a percent of principal amount Debt Instrument, Issuance Price, Percentage Debt Instrument, Issuance Price, Percentage Right-of-use assets acquired through operating leases Right-of-Use Asset Obtained in Exchange for Operating Lease Liability Debt Instrument, Interest Rate Period [Domain] Debt Instrument, Interest Rate Period [Domain] [Domain] for Debt Instrument, Interest Rate Period [Axis] Vesting percentage Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage Commitments and Contingencies Disclosure [Abstract] Commitments and Contingencies Disclosure [Abstract] Notes receivable and warrants received for entering into agreements Other Significant Noncash Transaction, Value of Consideration Received Aircraft fuel Fuel Costs 2022 Number Of Aircrafts Expected To Take Delivery, Year One Number Of Aircrafts Expected To Take Delivery, Year One Entity Interactive Data Current Entity Interactive Data Current Available under revolving credit facility Line of Credit Facility, Remaining Borrowing Capacity 2023 Number Of Aircrafts Expected To Take Delivery, Year Two Number Of Aircrafts Expected To Take Delivery, Year Two Loss per share, basic (in dollars per share) Earnings Per Share, Basic Indefinite-lived Intangible Assets, Major Class Name [Domain] Indefinite-lived Intangible Assets, Major Class Name [Domain] Employee benefit plans Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, after Tax REVENUE Revenue from Contract with Customer [Text Block] Document Type Document Type 2022 Long-Term Debt, Maturity, Year One Operating Revenue by Geographic Region Disaggregation of Revenue [Table Text Block] Class A Pass-Through Certificates Issued February 2021 Class A Pass-Through Certificates Issued February 2021 [Member] Class A Pass-Through Certificates Issued February 2021 DIP Loan Debtor-In-Possession Loan (DIP Loan) [Member] Debtor-In-Possession Loan (DIP Loan) Aircraft fuel, spare, parts and supplies - obsolescence allowance Airline Related Inventory, Valuation Reserves Fair Value Measurement [Domain] Fair Value Measurement [Domain] Entity Current Reporting Status Entity Current Reporting Status Pension liability Liability, Defined Benefit Pension Plan, Noncurrent Adoption of New Accounting Standard Cumulative Effect, Period of Adoption, Adjustment [Member] Flight Equipment Flight Equipment [Member] 2022 Unrecorded Unconditional Purchase Obligation, to be Paid, Year One Receivables, less allowance for credit losses (2021 — $71; 2020 — $78) Receivables, Net, Current Unconditional Purchase Obligation, Category of Goods or Services Acquired [Domain] Unconditional Purchase Obligation, Category of Goods or Services Acquired [Domain] Total debt recorded Long-term Debt, Gross Long-term debt Debt Long-term debt Long-term Debt (Gains) losses 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. Level 1 Fair Value, Inputs, Level 1 [Member] Cash Flows from Investing Activities: Net Cash Provided by (Used in) Investing Activities [Abstract] Document Transition Report Document Transition Report Income Tax Disclosure [Abstract] Income Tax Disclosure [Abstract] Total liabilities and stockholders' equity Liabilities and Equity Flight equipment Flight Equipment, Gross Other Income and Expenses [Abstract] Other Income and Expenses [Abstract] (Receivable from) Payable to Related Parties, Net Receivables from Stockholder [Member] Republic Republic [Member] Republic Scenario [Axis] Scenario [Axis] U.S. government and agency notes US Government Agencies Debt Securities [Member] LIABILITIES AND STOCKHOLDERS' EQUITY Liabilities and Equity [Abstract] Remaining term of debt Debt Instrument Remaining Terms Years remaining on debt instruments. Operating property and equipment: Property, Plant and Equipment, Net [Abstract] Aggregate maximum possible combined put payment and guarantee amount Loans Receivable, Aggregate Maximum Payment And Guarantee Amount Loans Receivable, Aggregate Maximum Payment And Guarantee Amount Amounts reclassified to earnings Reclassification from AOCI, Current Period, Tax LOSS PER SHARE Earnings Per Share [Text Block] Repurchases of common stock Treasury Stock, Value, Acquired, Cost Method Equity method investment, ownership percentage Equity Method Investment, Ownership Percentage PSP2 Payroll Support Program Extension Agreement (PSP2) [Member] Payroll Support Program Extension Agreement (PSP2) Standby Letters of Credit Standby Letters of Credit [Member] Minimum Minimum [Member] Aircraft Mortgage Debt Aircraft Mortgage Debt [Member] Aircraft Mortgage Debt [Member] Balance Sheet Location [Domain] Balance Sheet Location [Domain] Class of Warrant or Right [Line Items] Class of Warrant or Right [Line Items] Indefinite-lived Intangible Assets [Axis] Indefinite-lived Intangible Assets [Axis] Airbus A319 Airbus A319s [Member] Airbus A319s [Member] Class of Warrant or Right [Domain] Class of Warrant or Right [Domain] Cumulative Effect, Period of Adoption [Axis] Cumulative Effect, Period of Adoption [Axis] Part-Time Employees Part-Time Employees [Member] Part-Time Employees Other assets: Other Assets, Noncurrent [Abstract] Trading Symbol Trading Symbol Amounts reclassified to earnings Reclassification from AOCI, Current Period, Net of Tax, Attributable to Parent Deferred income taxes Deferred Income Tax Assets, Net Current liabilities: Liabilities, Current [Abstract] 2025 Long-Term Debt, Maturity, Year Four Class of Warrant or Right [Table] Class of Warrant or Right [Table] Issuance of common stock Stock Issued During Period, Value, New Issues Restructuring Plan [Domain] Restructuring Plan [Domain] Level 3 Fair Value, Inputs, Level 3 [Member] Less — Accumulated depreciation and amortization Property, Plant, and Equipment and Finance Lease Right-of-Use Asset, Accumulated Depreciation and Amortization Aircraft fuel, spare parts and supplies, less obsolescence allowance (2021 — $518; 2020 — $478) Airline Related Inventory, Net Aggregate balance Contractual Obligation Issuance of common stock (in shares) Number of shares issued (in shares) Stock Issued During Period, Shares, New Issues Number of aircraft temporarily removed Number Of Aircraft Temporarily Removed Number Of Aircraft Temporarily Removed Common stock Common Stock, Value, Issued Disaggregation of Revenue [Line Items] Disaggregation of Revenue [Line Items] Total nonoperating expense, net Nonoperating Income (Expense) Other Postretirement Benefits Other Postretirement Benefits Other Postretirement Benefits Plan [Member] Commitments and contingencies Commitments and Contingencies Accumulated other comprehensive loss Accumulated Other Comprehensive Income (Loss), Net of Tax Carrying Values and Estimated Fair Values of Financial Instruments Fair Value, by Balance Sheet Grouping [Table Text Block] Receivables - allowance for credit losses Accounts Receivable, Allowance for Credit Loss, Current Capital Commitments Capital Addition Purchase Commitments [Member] Total net other charges Gain (Loss) On Net Charges Gain (Loss) On Net Charges Frequent Flyer Frequent Flyer Program [Member] Frequent Flyer Program [Member] Regional capacity purchase Airline, Capacity Purchase Arrangements Employee Classification [Domain] Employee Classification [Domain] Employee Classification EMPLOYEE BENEFIT PLANS Compensation and Employee Benefit Plans [Text Block] Aircraft maintenance materials and outside repairs Aircraft Maintenance, Materials, and Repairs Fair Value [Table] Fair Value [Table] Fair Value [Table] Document Period End Date Document Period End Date Full-Time Employees Full-Time Employees [Member] Full-Time Employees Frequent Flyer Deferred Revenue [Roll Forward] Movement In Contract With Customer Liability [Roll Forward] Movement In Contract With Customer Liability [Roll Forward] Total operating expense Costs and Expenses Class of Stock [Axis] Class of Stock [Axis] Entity Registrant Name Entity Registrant Name Other financial liabilities from sale-leasebacks Financial Liabilities, Sale-Leaseback Transactions, Noncurrent Financial Liabilities, Sale-Leaseback Transactions, Noncurrent Collaborative Arrangement and Arrangement Other than Collaborative [Axis] Collaborative Arrangement and Arrangement Other than Collaborative [Axis] Number of shares of common stock (in shares) Class of Warrant or Right, Outstanding Payable to parent Receivable from Shareholders or Affiliates for Issuance of Capital Stock Interest expense Interest Costs Incurred Number of shares issuable (in shares) Sale Of Stock, Number Of Shares Issuable Under Agreement Sale Of Stock, Number Of Shares Issuable Under Agreement Champlain Champlain [Member] Champlain 2024 Unrecorded Unconditional Purchase Obligation, to be Paid, Year Three Balance Balance AOCI before Tax, Attributable to Parent Capital expenditures, net of flight equipment purchase deposit returns Payments to Acquire Productive Assets Changes in value Other Comprehensive Income (Loss) before Reclassifications, Tax Prepaid expenses and other Prepaid Expense and Other Assets, Current Years 1 through 5 Debt Instrument, Interest Rate Period, Years 1 Through 5 [Member] Debt Instrument, Interest Rate Period, Years 1 Through 5 [Member] Financial Instrument [Axis] Financial Instrument [Axis] Operating revenue Revenue from Contract with Customer, Excluding Assessed Tax Airbus A321neo Airbus A321neo [Member] Airbus A321neo Airbus A350 Airbus A350 [Member] Airbus A350 [Member] PSP3 Note Payroll Support Program 3 (PSP3) Note [Member] Payroll Support Program 3 (PSP3) Note Carrying Amount Reported Value Measurement [Member] Equity stake in Azul Equity Securities, Ownership Percentage Equity Securities, Ownership Percentage Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Axis] Equity [Abstract] Equity [Abstract] One-time per employee contribution for special termination benefits related to VSL programs Restructuring Programs, One-Time Contribution Per Employee Restructuring Programs, One-Time Contribution Per Employee Pass-Through Certificates Pass-Through Certificates [Member] Pass-Through Certificates [Member] United Airlines, Inc. United Air Lines Inc [Member] United Airlines, Inc. [Member] Interest income Investment Income, Interest Common Stock Common Stock [Member] Variable Rate [Axis] Variable Rate [Axis] 2026 Notes and 2029 Notes Senior Secured Notes Due 2026 And Senior Secured Notes Due 2029 [Member] Senior Secured Notes Due 2026 And Senior Secured Notes Due 2029 Changes in value OCI, before Reclassifications, Net of Tax, Attributable to Parent Operating loss Operating Income (Loss) Current maturities of operating leases Operating Lease, Liability, Current Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] SPECIAL CHARGES (CREDITS) Restructuring and Related Activities Disclosure [Text Block] Variable Rate [Domain] Variable Rate [Domain] PSP1 Warrants Payroll Support Program 1 (PSP1) Warrants [Member] Payroll Support Program 1 (PSP1) Warrants Purchase deposits for flight equipment Deposits on Flight Equipment Total AOCI Attributable to Parent, Net of Tax [Roll Forward] Additional Capital Invested Additional Paid-in Capital [Member] Cash and cash equivalents Cash and Cash Equivalents, at Carrying Value Operating Lease Right-of-Use Assets Operating Lease, Right-Of-Use Asset [Member] Operating Lease, Right-Of-Use Asset Class A Clear Warrants Class A Clear Warrants [Member] Class A Clear Warrants Tax-Exempt Special Facilities Revenue Bonds Tax Exempt Bonds [Member] Tax Exempt Bonds [Member] Long-term Debt, Type [Domain] Long-term Debt, Type [Domain] Reconciliation of cash, cash equivalents and restricted cash: Cash and Cash Equivalents [Abstract] Treasury Stock Treasury Stock [Member] Total commitments Unrecorded Unconditional Purchase Obligation Commitments and Contingencies [Table] Commitments and Contingencies [Table] Commitments And Contingencies [Table] After 2025 Long-Term Debt, Maturity, After Year Four Long-Term Debt, Maturity, After Year Four Collaborative Arrangement and Arrangement Other than Collaborative [Domain] Collaborative Arrangement and Arrangement Other than Collaborative [Domain] Number of aircraft delivered Number Of Aircraft Received Number Of Aircraft Received Impairment of assets Asset Impairment Charges Number of securities called by warrants (in shares) Class of Warrant or Right, Number of Securities Called by Warrants or Rights B-737-Max B-737-Max [Member] Lease modifications and lease conversions Lease Conversions From Operating Lease Recorded Property Plant And Equipment Lease Conversions From Operating Lease Recorded Property Plant And Equipment Miscellaneous, net Other Nonoperating Income (Expense) Long-term debt Long-term Debt, Fair Value Airline Destination [Domain] Airline Destination [Domain] Other, net Payments for (Proceeds from) Other Investing Activities Other Other Liabilities, Current Maximum Maximum [Member] Entity Information [Line Items] Entity Information [Line Items] Loss Contingency, Nature [Domain] Loss Contingency, Nature [Domain] Term of award Share-based Compensation Arrangement by Share-based Payment Award, Terms of Award Boom Warrants Boom Warrants [Member] Boom Warrants Chase and Other Partner Agreements Chase And Other Partner Agreements [Member] Chase And Other Partner Agreements [Member] PSP2 Note Payroll Support Program 2 (PSP2) Note [Member] Payroll Support Program 2 (PSP2) Note Legal Entity [Axis] Legal Entity [Axis] Aircraft [Domain] Aircraft [Domain] Award Type Award Type [Axis] Total funding provided under the Payroll Support Program Payroll Support Program, Funding Provided Payroll Support Program, Total Funding Provided Cash Flows from Financing Activities: Net Cash Provided by (Used in) Financing Activities [Abstract] Total stockholders' equity Balance Balance Stockholders' Equity Attributable to Parent Common shares, issued (in shares) Common Stock, Shares, Issued Pacific Pacific Destination [Member] Notes receivable Receivable with Imputed Interest, Face Amount Term Loan Receivable Term Loan Receivable [Member] Term Loan Receivable [Member] Repurchases of common 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Contingency Nature [Axis] Loss Contingency Nature [Axis] City Area Code City Area Code Retained earnings Retained Earnings (Accumulated Deficit) Routes Use Rights [Member] Schedule of Defined Benefit Plans Disclosures [Table] Schedule of Defined Benefit Plans Disclosures [Table] Unusual or Infrequent Items, or Both [Abstract] Unusual or Infrequent Items, or Both [Abstract] RSUs Restricted Stock Units (RSUs) [Member] Statement of Stockholders' Equity [Abstract] Statement of Stockholders' Equity [Abstract] Equity method investments Equity Method Investments Income Statement [Abstract] Income Statement [Abstract] Amendment Flag Amendment Flag Fair Value Estimate of Fair Value Measurement [Member] Asset Class [Domain] Asset Class [Domain] Interest capitalized Interest Costs Capitalized Adjustment Nonoperating debt extinguishment and modification fees Gain (Loss) On Debt Extinguishment And Modification, Nonoperating Gain (Loss) On Debt Extinguishment And Modification, Nonoperating Senior Secured Revolving Credit Facility due 2025 Senior Secured Revolving Credit Facility Due 2025 [Member] Senior Secured Revolving Credit Facility Due 2025 Short-term investments Short-term Investments Income tax benefit Income Tax Expense (Benefit) Passenger revenue Passenger [Member] Payroll Support Program 2 (PSP2) Warrants PSP2 Warrants Payroll Support Program 2 (PSP2) Warrants [Member] Payroll Support Program 2 (PSP2) Warrants Total other liabilities and deferred credits Other Liabilities And Deferred Credits, Noncurrent Other Liabilities And Deferred Credits, Noncurrent Unsecured Debt Unsecured Debt [Member] Proceeds from issuance of debt, net of discounts and fees Total proceeds received from issuance of debt Proceeds from Issuance of Long-term Debt Equity Components [Axis] Equity Components [Axis] Accumulated Other Comprehensive Income (Loss) [Table] Accumulated Other Comprehensive Income (Loss) [Table] Aircraft Type [Axis] Aircraft Type [Axis] Fair Value Disclosures [Abstract] 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Valuation allowance Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Amount Schedule of Stock by Class [Table] Schedule of Stock by Class [Table] Entity File Number Entity File Number Warrants issued Warrants recorded within stockholders' equity Adjustments to Additional Paid in Capital, Warrant Issued 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] Statement of Financial Position [Abstract] Statement of Financial Position [Abstract] Number of aircraft operated Number of Aircraft Operated Government assistance received through unsecured loans Proceeds from Issuance of Unsecured Debt Current maturities of long-term debt Long-term Debt, Current Maturities Product and Service [Axis] Product and Service [Axis] Summary of Warrants Outstanding Schedule of Stockholders' Equity Note, Warrants or Rights [Table Text Block] Fair Value, by Balance Sheet Grouping [Table] Fair Value, by Balance Sheet Grouping [Table] Entity Incorporation, State or Country Code Entity Incorporation, State or Country Code Entity Small Business Entity Small Business Restructuring Plan [Axis] Restructuring Plan [Axis] Investment carrying value Equity Securities without Readily Determinable Fair Value, Amount Fulcrum BioEnergy Inc. Fulcrum BioEnergy Inc. [Member] Fulcrum BioEnergy Inc. Number of ADRs that may be put into United (in shares) Loans Receivable, Agreement, Put Option, Deposit Receipts Loans Receivable, Agreement, Put Option, Deposit Receipts Equity Component [Domain] Equity Component [Domain] Stock issued for share-based awards, net of shares withheld for tax (in shares) Shares Issued, Shares, Share-based Payment Arrangement, after Forfeiture Other Stockholders' Equity, Other Unusual Or Infrequent Events, Government Assistance Programs [Domain] Unusual Or Infrequent Events, Government Assistance Programs [Domain] Unusual Or Infrequent Events, Government Assistance Programs Statement [Line Items] Statement [Line Items] Total operating property and equipment, net Property, Plant, and Equipment and Finance Lease Right-of-Use Asset, after Accumulated Depreciation and Amortization Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Restricted cash Restricted cash — Non-Current Restricted Cash, Noncurrent Income tax expense (benefit), net of valuation allowance Income Tax Expense (Benefit) Special Charges Income tax expense (benefit) special charges. 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Stockholders, Diluted PSP3 Warrants Payroll Support Program 3 (PSP3) Warrants [Member] Payroll Support Program 3 (PSP3) Warrants Loss available to common stockholders, basic Net Income (Loss) Available to Common Stockholders, Basic Product and Service [Domain] Product and Service [Domain] Stated interest rate Stated interest rate Debt Instrument, Interest Rate, Stated Percentage 2029 Notes Senior Secured Notes Due 2029 [Member] Senior Secured Notes Due 2029 Dividend to UAL Capital Contributions To Parent Capital Contributions To Parent Airbus A321XLR Airbus A321XLR [Member] Airbus A321XLR [Member] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Revolving Credit Facility Revolving Credit Facility [Member] Term Loan B Facility due 2028 Term Loan B Facility Due 2028 [Member] Term Loan B Facility Due 2028 Cumulative Effect, Period of Adoption [Domain] Cumulative Effect, Period of 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(Loss) Due To Settlement, Restructuring And Special And Contractual Termination Benefits Basic weighted-average shares outstanding (in shares) Weighted Average Number of Shares Outstanding, Basic Loss per share, diluted (in dollars per share) Earnings Per Share, Diluted Employee-related Liabilities [Abstract] Employee-related Liabilities [Abstract] 2023 Unrecorded Unconditional Purchase Obligation, to be Paid, Year Two Unrecorded Unconditional Purchase Obligation by Category of Item Purchased [Axis] Unrecorded Unconditional Purchase Obligation by Category of Item Purchased [Axis] Service cost Defined Benefit Plan, Service Cost Before Tax AOCI Attributable To Parent, Before Tax [Roll Forward] AOCI Attributable To Parent, Before Tax [Roll Forward] Quarterly installment repayment as a percent of the original principal amount Debt Instrument, Quarterly Installment Percentage Debt Instrument, Quarterly Installment Percentage Funding provided through loans under the Payroll Support Program 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treasury, at cost Treasury Stock, Value Other comprehensive income (loss), net of tax: Other Comprehensive Income (Loss), Net of Tax [Abstract] Investments and other Other Comprehensive Income, Investments and Other, Net of Tax Other Comprehensive Income, Investments and Other, Net of Tax Vesting period Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period Fair Value [Line Items] Fair Value [Line Items] Fair Value [Line Items] Total operating and nonoperating special charges (credits) and unrealized (gains) losses on investments, net Special Charges And Losses On Financial Instruments, Operating And Nonoperating, Before Tax Special Charges And Losses On Financial Instruments, Operating And Nonoperating, Before Tax Dividend to UAL Payments Of Dividends To Parent Company Payments of dividends to parent company. Other operating expenses Other Cost and Expense, Operating Number of days used to compute performance period average closing price of restricted stock units Determination Period Average Closing Price The time period over which the stock closing prices are averaged to arrive at a per-share valuation for equity based awards such as Restricted Stock Units, Performance Share and other equity based awards. Restricted cash - non-current Restricted Cash, Noncurrent, Fair Value Disclosure Restricted Cash Fair Value Disclosure Corporate debt Corporate Debt Corporate Debt Securities [Member] Other property and equipment Property, Plant and Equipment, Other, Gross FINANCIAL INSTRUMENTS AND FAIR VALUE MEASUREMENTS Fair Value Disclosures [Text Block] Deferred Taxes AOCI Attributable To Parent, Tax [Roll Forward] AOCI Attributable To Parent, Tax [Roll Forward] Accounts payable Accounts Payable, Current 2020 ATM Offering 2020 ATM Offering [Member] 2020 ATM Offering Depreciation and amortization Depreciation, Depletion and Amortization 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] Entities [Table] Entities [Table] Time-Vested RSUs Time-Vested Restricted Stock Units (RSUs) [Member] Time-Vested Restricted Stock Units (RSUs) [Member] Floating Rate Debt Floating Rate Debt [Member] Floating Rate Debt [Member] Other investment ownership Interest Equity Securities Without Readily Determinable Fair Value, Ownership Interest Equity Securities Without Readily Determinable Fair Value, Ownership Interest Accumulated Other Comprehensive Income (Loss) Accumulated Other Comprehensive Income (Loss) AOCI Attributable to Parent [Member] Components of Special Charges Restructuring and Related Costs [Table Text Block] Common shares, outstanding (in shares) Balance (in shares) Balance (in shares) Common Stock, Shares, Outstanding Financial Instruments [Domain] Financial Instruments [Domain] After 2025 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 Operating revenue: Revenues [Abstract] Regional CPAs Airline Capacity Purchase Arrangements [Member] Boeing 737 MAX 10 Boeing 737 MAX 10 [Member] Boeing 737 MAX 10 Changes in value OCI, before Reclassifications, before Tax, Attributable to Parent Other operating revenue Other Operating Revenue Product and Service, Other [Member] CARES Act grant Unusual or Infrequent Item, or Both, Gain, Gross 2025 Unrecorded Unconditional Purchase Obligation, to be Paid, Year Four Term of debt Debt Instrument, Term Market price of common stock at fifth anniversary (in dollars per share) Loans Receivable, Guarantee And Payout Share Price At Fifth Anniversary Loans Receivable, Guarantee And Payout Share Price At Fifth Anniversary Short-term investments Investments, Fair Value Disclosure Investing and Financing Activities Not Affecting Cash: Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract] Long-term Purchase Commitment [Line Items] Long-term Purchase Commitment [Line Items] Details of Pass Through Trusts Schedule of Debt Instruments Pass Through Trusts [Table Text Block] Schedule of Debt Instruments Pass Through Trusts Current/Long-Term Obligations under Operating Leases Operating Lease, Liability [Member] Operating Lease, Liability Other Other Liabilities, Noncurrent Aircraft rent Aircraft Rental Cargo Cargo and Freight [Member] Repurchases of common stock (in shares) Treasury Stock, Shares, Acquired Debt Instrument [Line Items] Debt Instrument [Line Items] Clear Secure, Inc. Clear Secure, Inc. [Member] Clear Secure, Inc. Payments of long-term debt, finance leases and other financing liabilities Repayments of Long-term Debt Earnings Per Share [Abstract] Earnings Per Share [Abstract] Gain (loss) on equity securities Equity Securities, FV-NI, Unrealized Gain (Loss) 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 Document Quarterly Report Document Quarterly Report Warrant exercise price (in dollars per share) Exercise price (in dollars per share) Class of Warrant or Right, Exercise Price of Warrants or Rights Unusual Or Infrequent Events, Government Assistance Programs [Axis] Unusual Or Infrequent Events, Government Assistance Programs [Axis] Unusual Or Infrequent Events, Government Assistance Programs Investments in affiliates and other, less allowance for credit losses (2021 — $606; 2020 — $522) Investments and Other Noncurrent Assets Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Preferred Stock Purchase Rights Warrant [Member] Operating expense: Costs and Expenses [Abstract] Warrant term Warrants and Rights Outstanding, Term Government assistance received Proceeds From Government Assistance Proceeds From Government Assistance Long-term debt Long-term Debt, Excluding Current Maturities Non-travel miles redeemed (Other operating revenue) Non-Travel Miles Redemption, Frequent Flyer Deferred Revenue Non-travel miles redemption, frequent flyer deferred revenue. Share-based compensation expense Share-based Payment Arrangement, Expense Unusual or Infrequent Item, or Both [Table] Unusual or Infrequent Item, or Both [Table] Commitments and Contingencies [Line Items] Commitments and Contingencies [Line Items] Commitments And Contingencies [Line Items] Last Six Months of 2021 Number Of Aircrafts Expected To Take Delivery, Remainder Of Year Number Of Aircrafts Expected To Take Delivery, Remainder Of Year Number of aircraft committed to purchase Number of firm commitments Unrecorded Unconditional Purchase Obligation, Minimum Quantity Required Document Fiscal Period Focus Document Fiscal Period Focus Long-term Purchase Commitment [Table] Long-term Purchase Commitment [Table] Effective income tax rate Effective Income Tax Rate Reconciliation, Percent Landing fees and other rent Landing Fees and Other Rentals Salaries and related costs Labor and Related Expense Investments [Domain] Investments [Domain] Years 6 through 10 Debt Instrument, Interest Rate Period, Years 6 Through 10 [Member] Debt Instrument, Interest Rate Period, Years 6 Through 10 [Member] Restricted cash Restricted cash — Current Restricted Cash, Current Unrecorded Unconditional Purchase Obligation [Line Items] Unrecorded Unconditional Purchase Obligation [Line Items] Counterparty Name [Axis] Counterparty Name [Axis] Funding provided through direct grants under the Payroll Support Program Payroll Support Program, Funding Provided, Amounts Received Through Direct Grants Payroll Support Program, Funding Provided, Amounts Received Through Direct Grants CARES Act Loan Warrants CARES Act Loan Warrants [Member] CARES Act Loan Warrants Class of Warrant or Right [Axis] Class of Warrant or Right [Axis] Cash, cash equivalents and restricted cash at beginning of the period Cash, cash equivalents and restricted cash at end of the period Total cash, cash equivalents and restricted cash Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents Common stock, par value (in dollars per share) Common Stock, Par or Stated Value Per Share Aggregate principal amount of guarantee Guarantor Obligations, Maximum Exposure, Undiscounted Defined Benefit Plan Disclosure [Line Items] Defined Benefit Plan Disclosure [Line Items] Restricted cash - current Restricted Cash, Current, Fair Value Disclosure Restricted Cash, Current, Fair Value Disclosure Current assets: Assets, Current [Abstract] Statement of Comprehensive Income [Abstract] Statement of Comprehensive Income [Abstract] Other, net Proceeds from (Payments for) Other Financing Activities Entity Central Index Key Entity Central Index Key ETCs and FFCs Electronic Travel Certificates (ETCs) And Future Flight Credits (FFCs) [Member] Electronic Travel Certificates (ETCs) And Future Flight Credits (FFCs) Gain for the change in fair value of certain derivative assets Derivative, Gain on Derivative LIBOR London Interbank Offered Rate (LIBOR) [Member] Security Exchange Name Security Exchange Name Percentage of employees represented by various U.S. labor organizations Percentage Of Employees Represented By Labor Organizations Percentage of employees represented by labor organizations Accumulated Other Comprehensive Income (Loss) [Line Items] Accumulated Other Comprehensive Income (Loss) [Line Items] Cash and cash equivalents Cash and Cash Equivalents, Fair Value Disclosure Amounts reclassified to earnings Reclassification from AOCI, Current Period, before Tax, Attributable to Parent Advance ticket sales Contract With Customer, Liability, Current, Advance Ticket Sales Contract With Customer, Liability, Current, Advance Ticket Sales Diluted weighted-average shares outstanding (in shares) Weighted Average Number of Shares Outstanding, Diluted Carrying value of warrants Warrants and Rights Outstanding Total other comprehensive income (loss), net of tax Other comprehensive income (loss) Other Comprehensive Income (Loss), Net of Tax Distribution expenses Selling Expense Measured on a Recurring Basis Fair Value, Recurring [Member] INCOME TAXES Income Tax Disclosure [Text Block] Revenue From Contract With Customer [Line Items] Revenue From Contract With Customer [Line Items] [Line Items] for Revenue From Contract With Customer [Table] [Table] Long-term Debt, Type [Axis] Long-term Debt, Type [Axis] Current Fiscal Year End Date Current Fiscal Year End Date Percent spread on variable rate Debt Instrument, Basis Spread on Variable Rate Unusual or Infrequent Item, or Both [Line Items] Unusual or Infrequent Item, or Both [Line Items] Components of Net Periodic Benefit Cost Schedule of Net Benefit Costs [Table Text Block] Atlantic Atlantic Destination [Member] Measurement Basis [Axis] Measurement Basis [Axis] Last six months of 2021 Unrecorded Unconditional Purchase Obligation, to be Paid, Remainder of Fiscal Year Special termination benefits Special termination benefits related to VSL 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 Fair Value of Financial Instruments Fair Value of Financial Instruments, Policy [Policy Text Block] Loan amount Financing Receivable, Face Amount Financing Receivable, Face Amount Statement of Cash Flows [Abstract] Statement of Cash Flows [Abstract] Nonoperating income (expense): Nonoperating Income (Expense) [Abstract] Domestic (U.S. and Canada) Domestic Destination [Member] Class of Stock [Line Items] Class of Stock [Line Items] Credit Facility [Axis] Credit Facility [Axis] Net cash used in investing activities Net Cash Provided by (Used in) Investing Activities Summary of Commitments Unrecorded Unconditional Purchase Obligations Disclosure [Table Text Block] Portion at Fair Value Measurement Portion at Fair Value Measurement [Member] Cash Flows from Operating Activities: Net Cash Provided by (Used in) Operating Activities [Abstract] Total current liabilities Liabilities, Current Class of Stock [Domain] Class of Stock [Domain] Interest rate Financing Receivable, Stated Interest Rate Financing Receivable, Stated Interest Rate Maximum borrowing capacity Line of Credit Facility, Maximum Borrowing Capacity Entity Address, Postal Zip Code Entity Address, Postal Zip Code Advance Ticket Sales Advance Ticket Sales [Member] Advance Ticket Sales [Member] Credit Agreement Revolving Credit Facility Under The Credit Agreement [Member] Revolving Credit Facility Under The Credit Agreement Loan balance Financing Receivable, before Allowance for Credit Loss Performance-Based RSUs Performance-Based Restricted Stock Units (RSUs) [Member] Performance-Based Restricted Stock Units (RSUs) [Member] Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] Title of 12(b) Security Title of 12(b) Security UAL And United UAL And United [Member] UAL And United [Member] Statement [Table] Statement [Table] Asset-backed securities Asset-Backed Securities Asset-backed Securities [Member] Payroll Support Program deferred credit Government Assistance, Deferred Credit, Current Government Assistance, Deferred Credit, Current Unrecognized share-based compensation Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount Ancillary Fees Passenger - Ancillary Fees [Member] Passenger - Ancillary Fees [Member] Latin America Latin America Destination [Member] Statistical Measurement [Axis] Statistical Measurement [Axis] Travel miles redeemed (Passenger revenue) Travel Miles Redemption, Frequent Flyer Deferred Revenue Travel miles redemption, frequent flyer deferred revenue. Term Loan Facility Term Loan Due 2024 [Member] Term Loan Due 2024 Cover [Abstract] Cover [Abstract] BRW BRW Aviation Holding LLC And BRW Aviation LLC (“BRW”) [Member] BRW Aviation Holding LLC and BRW Aviation LLC (“BRW”) [Member] Investments in affiliates and other - allowance for credit losses Financing Receivable, Allowance for Credit Loss Preferred Stock Preferred Stock [Member] Long-term obligations under finance leases Finance Lease, Liability, Noncurrent Goodwill Goodwill Voluntary Separation Leave Programs Voluntary Separation Leave (VSL) Programs [Member] Voluntary Separation Leave (VSL) Programs Scenario [Domain] Scenario [Domain] Pension Benefits Pension Benefits Pension Plan [Member] Archer Warrants Archer Warrants [Member] Archer Warrants Unamortized debt discount Debt Instrument, Unamortized Discount Pension and Other Postretirement Liabilities Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member] Number of impaired aircraft Number Of Impaired Aircraft Number Of Impaired Aircraft DEBT Long-term Debt [Text Block] Accounting Standards Update 2016-13 [Member]