Commitments and Contingencies - Narrative (Details) $ in Millions		9 Months Ended
Apr. 17, 2024	Sep. 30, 2024 USD ($) employee aircraft
Commitments and Contingencies [Line Items]
Leases not yet commenced		$ 4,000
Terms of leases not yet commenced		12 years
United Airlines, Inc.
Commitments and Contingencies [Line Items]
Number of employees \| employee		106,500
Percentage of employees represented by various U.S. labor organizations		82.00%
Proposed extension period for technician labor contracts	4 years
Tax-Exempt Special Facilities Revenue Bonds
Commitments and Contingencies [Line Items]
Aggregate principal amount of guarantee		$ 1,800
Aircraft Mortgage Debt
Commitments and Contingencies [Line Items]
Aggregate principal amount of guarantee		66
Floating Rate Debt
Commitments and Contingencies [Line Items]
Long-term debt		$ 8,500
Remaining term of debt		12 years
Loans and Leases from Non-U.S. Entities
Commitments and Contingencies [Line Items]
Remaining term of debt		12 years
Aggregate balance		$ 5,400
A321neo
Commitments and Contingencies [Line Items]
Number of aircrafts with expected deliveries in 2026 and 2027 \| aircraft		40

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Commitments And Contingencies [Line Items]

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Number Of Aircrafts Expected To Take Delivery, Year Two And Three

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

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