Fair Value Measurements and Other Investments - Narrative (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt, fair value	$ 2,700	$ 2,300
Level 3 | American Airlines, Inc.
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt, fair value		550
Level 2 | Fair Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt, fair value	40,325	30,454
Level 2 | Convertible Note | Fair Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt, fair value	1,700	1,200
Level 2 | American Airlines, Inc. | Fair Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt, fair value	$ 35,328	$ 27,193