Basis of Presentation and Summary of Significant Accounting Policies - Significant Contract Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Disaggregation of Revenue [Line Items]
Contract balances, liability	$ 13,952	$ 13,423
Loyalty program liability
Disaggregation of Revenue [Line Items]
Contract balances, liability	9,195	8,615
Air traffic liability
Disaggregation of Revenue [Line Items]
Contract balances, liability	4,757	4,808
American Airlines, Inc.
Disaggregation of Revenue [Line Items]
Contract balances, liability	13,952	13,423
American Airlines, Inc. | Loyalty program liability
Disaggregation of Revenue [Line Items]
Contract balances, liability	9,195	8,615
American Airlines, Inc. | Air traffic liability
Disaggregation of Revenue [Line Items]
Contract balances, liability	$ 4,757	$ 4,808