Basis of Presentation and Summary of Significant Accounting Policies - Changes in Loyalty Program Liability (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Movement In Contract With Customer, Liability [Roll Forward]
Beginning balance	$ 13,423
Ending balance	13,952
Loyalty program liability
Movement In Contract With Customer, Liability [Roll Forward]
Beginning balance	8,615
Deferral of revenue	1,812
Recognition of revenue	(1,232)
Ending balance	$ 9,195
Inactive period before expiration of mileage credits	18 months
Customer liabilities	$ 2,033	$ 3,193
American Airlines, Inc.
Movement In Contract With Customer, Liability [Roll Forward]
Beginning balance	13,423
Ending balance	13,952
American Airlines, Inc. | Loyalty program liability
Movement In Contract With Customer, Liability [Roll Forward]
Beginning balance	8,615
Deferral of revenue	1,812
Recognition of revenue	(1,232)
Ending balance	$ 9,195
Inactive period before expiration of mileage credits	18 months
Customer liabilities	$ 2,033	$ 3,193