Employee Benefit Plans - Schedule of Accumulated Benefit Obligations Exceeding Fair Value of Plan Assets (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation	$ 19,812	$ 18,327
Accumulated benefit obligation	19,799	18,315
Fair value of plan assets	13,557	12,862
Retiree Medical and  Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Accumulated postretirement benefit obligation	1,046	824
Fair value of plan assets	170	204
American Airlines, Inc. | Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation	19,690	18,215
Accumulated benefit obligation	19,678	18,204
Fair value of plan assets	13,477	12,794
American Airlines, Inc. | Retiree Medical and  Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Accumulated postretirement benefit obligation	1,046	824
Fair value of plan assets	$ 170	$ 204