Leases - Supplemental Cash Flow and Other Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from operating leases	$ 2,028	$ 2,013	$ 1,931
Operating cash flows from finance leases	39	43	48
Financing cash flows from finance leases	114	83	78
Non-cash transactions:
ROU assets acquired through operating leases	917	1,145	1,292
Operating lease conversion to finance lease	5	41	0
Property and equipment acquired through finance leases	11	20	0
Gain on sale leaseback transactions, net	107	107	59
American Airlines, Inc.
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from operating leases	2,015	1,996	1,914
Operating cash flows from finance leases	39	43	48
Financing cash flows from finance leases	114	83	78
Non-cash transactions:
ROU assets acquired through operating leases	898	1,144	1,258
Operating lease conversion to finance lease	5	41	0
Property and equipment acquired through finance leases	11	20	0
Gain on sale leaseback transactions, net	$ 107	$ 107	$ 59