Employee Benefit Plans - Fair Values of Retiree Medical and Other Postretirement Benefit Plans Assets by Asset Category (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Mutual funds | Non-U.S.
Defined Benefit Plan Disclosure [Line Items]
Actual plan asset allocations	26.00%	27.00%
Retiree Medical and  Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 170	$ 204	$ 225
Retiree Medical and  Other Postretirement Benefits | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	4	4
Retiree Medical and  Other Postretirement Benefits | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	166	200
Retiree Medical and  Other Postretirement Benefits | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Retiree Medical and  Other Postretirement Benefits | Money market fund
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	4	4
Retiree Medical and  Other Postretirement Benefits | Money market fund | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	4	4
Retiree Medical and  Other Postretirement Benefits | Money market fund | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Retiree Medical and  Other Postretirement Benefits | Money market fund | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Retiree Medical and  Other Postretirement Benefits | Mutual funds – AAL Class
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	166	200
Retiree Medical and  Other Postretirement Benefits | Mutual funds – AAL Class | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Retiree Medical and  Other Postretirement Benefits | Mutual funds – AAL Class | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	166	200
Retiree Medical and  Other Postretirement Benefits | Mutual funds – AAL Class | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 0	$ 0
Retiree Medical and  Other Postretirement Benefits | Mutual funds | Non-U.S.
Defined Benefit Plan Disclosure [Line Items]
Actual plan asset allocations	25.00%	24.00%
American Airlines, Inc. | Mutual funds | Non-U.S.
Defined Benefit Plan Disclosure [Line Items]
Actual plan asset allocations	25.00%	24.00%
American Airlines, Inc. | Retiree Medical and  Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 170	$ 204	$ 225
American Airlines, Inc. | Retiree Medical and  Other Postretirement Benefits | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	4	4
American Airlines, Inc. | Retiree Medical and  Other Postretirement Benefits | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	166	200
American Airlines, Inc. | Retiree Medical and  Other Postretirement Benefits | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
American Airlines, Inc. | Retiree Medical and  Other Postretirement Benefits | Money market fund
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	4	4
American Airlines, Inc. | Retiree Medical and  Other Postretirement Benefits | Money market fund | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	4	4
American Airlines, Inc. | Retiree Medical and  Other Postretirement Benefits | Money market fund | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
American Airlines, Inc. | Retiree Medical and  Other Postretirement Benefits | Money market fund | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
American Airlines, Inc. | Retiree Medical and  Other Postretirement Benefits | Mutual funds – AAL Class
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	166	200
American Airlines, Inc. | Retiree Medical and  Other Postretirement Benefits | Mutual funds – AAL Class | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
American Airlines, Inc. | Retiree Medical and  Other Postretirement Benefits | Mutual funds – AAL Class | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	166	200
American Airlines, Inc. | Retiree Medical and  Other Postretirement Benefits | Mutual funds – AAL Class | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 0	$ 0