Quarterly Financial Data - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Restructuring Cost and Reserve [Line Items]
Operating and nonoperating special items, net	$ (36)	$ 108
Merger integration expenses		85
Fleet restructuring expenses		39
Mark-to-market net unrealized gains (losses) on equity investments		42	$ (135)	$ 5	$ (104)
American Airlines, Inc.
Restructuring Cost and Reserve [Line Items]
Operating and nonoperating special items, net	$ (36)	108
Merger integration expenses		85
Fleet restructuring expenses		39
Mark-to-market net unrealized gains (losses) on equity investments		$ 42	$ (135)	$ 5	$ (104)