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Employee Benefit Plans - Defined Contribution Plans (Details) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Defined Contribution Plan Disclosure [Line Items]      
Contributions to defined contribution benefit plans $ 877 $ 851 $ 766
American Airlines, Inc. [Member]      
Defined Contribution Plan Disclosure [Line Items]      
Contributions to defined contribution benefit plans $ 856 $ 844 $ 761