Investments - Schedule of Equity Investments (Details) - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments	$ 119	$ 186
American Airlines, Inc.
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments	119	186
Equity Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total	495	541
Equity Securities | American Airlines, Inc.
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total	$ 495	$ 541
China Southern Airlines
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Ownership interest, fair value method investments	1.50%	1.50%
Carrying value, fair value method investments	$ 129	$ 115
China Southern Airlines | American Airlines, Inc.
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Ownership interest, fair value method investments	1.50%	1.50%
Carrying value, fair value method investments	$ 129	$ 115
Republic Airways Holdings Inc.
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Ownership interest, equity method investments	25.00%	25.00%
Carrying value, equity method investments	$ 247	$ 240
Republic Airways Holdings Inc. | American Airlines, Inc.
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Ownership interest, equity method investments	25.00%	25.00%
Carrying value, equity method investments	$ 247	$ 240