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Years remaining on debt instruments.

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Loans Receivable, Agreement, Put Options

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Loans Receivable, Guarantee And Payout Share Price At Fifth Anniversary

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Number Of Aircraft Expected Take Delivery Of, Original Estimate, Next Twelve Months

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Number Of Aircraft Expected To Take Delivery, Next Twelve Months

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Number Of Aircrafts Expected Take Delivery, Original Estimate, Previous Year

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Percentage of employees represented by labor organizations

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Amount of borrowing capacity currently available under the debt instrument (initial borrowing capacity less the amount of proceeds received).

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Amount of contractual obligation, including but not limited to, long-term debt, capital lease obligations, operating lease obligations, purchase obligations, and other commitments.

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Face (par) amount of debt instrument at time of issuance.

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The current carrying amount of the liability for the freestanding or embedded guarantor's obligations under the guarantee or each group of similar guarantees.

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Maximum potential amount of future payments (undiscounted) the guarantor could be required to make under the guarantee or each group of similar guarantees before reduction for potential recoveries under recourse or collateralization provisions.

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The minimum number of units that must be purchased, in connection with an unconditional purchase obligation that has not been recognized for financial reporting purposes.

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Commitments and Contingencies - Narrative (Details) $ / shares in Units, Employee in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($) Option	Dec. 31, 2019 $ / shares	Dec. 31, 2019 shares	Dec. 31, 2019 Employee	Dec. 31, 2019 commitment	Dec. 31, 2019 aircraft	Dec. 31, 2018 USD ($)
Commitments and Contingencies [Line Items]
Aggregate balance	$ 15,700,000,000
Number of call options to purchase regional jet aircraft \| Option	325
United Airlines, Inc.
Commitments and Contingencies [Line Items]
Number of employees \| Employee				96
Percentage of employees represented by various U.S. labor organizations	84.00%
United Airlines, Inc. \| Surety Bonds
Commitments and Contingencies [Line Items]
Long-term line of credit	$ 414,000,000
Tax-Exempt Special Facilities Revenue Bonds
Commitments and Contingencies [Line Items]
Guarantor obligations, maximum exposure	1,900,000,000
Tax-Exempt Special Facilities Revenue Bonds \| Indirect Guarantee of Indebtedness
Commitments and Contingencies [Line Items]
Guarantor obligations, maximum exposure	175,000,000
Contingent liabilities based on participation	1,900,000,000
Floating Rate Debt
Commitments and Contingencies [Line Items]
Debt instrument principal amount	$ 3,400,000,000
Debt instrument, remaining terms	11 years
Loans And Leases From Non U S Entities
Commitments and Contingencies [Line Items]
Debt instrument, remaining terms	11 years
Aggregate balance	$ 3,200,000,000
Aircraft Mortgage Debt
Commitments and Contingencies [Line Items]
Guarantor obligations, maximum exposure	132,000,000
Kingsland
Commitments and Contingencies [Line Items]
Number of shares that may be put to United (in shares) \| shares			144,800,000
Number of ADRs that may be put to United (in shares) \| shares			18,100,000
Market price of common stock at fifth anniversary (in dollars per share) \| $ / shares		$ 12
Aggregate maximum possible combined put payment and guarantee amount	217,000,000
Contingent liabilities based on participation							$ 31,000,000
Pass-Through Certificates
Commitments and Contingencies [Line Items]
Remaining proceeds from issuance of debt to be received in future periods	328,000,000
Debt instrument principal amount	2,234,000,000
Embraer E175
Commitments and Contingencies [Line Items]
Number of firm commitments					20	20
Number of aircraft scheduled for delivery \| aircraft						20
Airbus A319
Commitments and Contingencies [Line Items]
Number of firm commitments \| aircraft						20
Boeing 737-700
Commitments and Contingencies [Line Items]
Number of firm commitments \| aircraft						19
Boeing 737 MAX
Commitments and Contingencies [Line Items]
Number of firm commitments \| commitment					171
Number of aircraft scheduled for delivery \| aircraft						44
Number of aircraft the company planned to take delivery of in 2019 \| aircraft						16
Number of aircraft the company planned to take delivery of in 2020 \| aircraft						28
Letter of Credit \| United Airlines, Inc. \| Cash Collateralized Letters of Credit
Commitments and Contingencies [Line Items]
Long-term line of credit	$ 73,000,000