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Employee Benefit Plans - Schedule of Accumulated Benefit Obligations Exceeding Fair Value of Plan Assets (Detail) - USD ($)
$ in Millions
Dec. 31, 2017
Dec. 31, 2016
Pension Benefits [Member]    
Defined Benefit Plan Disclosure [Line Items]    
Projected benefit obligation (PBO) $ 18,245 $ 17,209
Accumulated benefit obligation (ABO) 18,235 17,197
Fair value of plan assets 11,364 9,986
ABO less fair value of plan assets 6,871 7,211
Retiree Medical And Other Postretirement Benefits [Member]    
Defined Benefit Plan Disclosure [Line Items]    
Accumulated postretirement benefit obligation (APBO) 1,011 990
Fair value of plan assets 295 266
American Airlines, Inc. [Member] | Pension Benefits [Member]    
Defined Benefit Plan Disclosure [Line Items]    
Projected benefit obligation (PBO) 18,144 17,119
Accumulated benefit obligation (ABO) 18,135 17,108
Fair value of plan assets 11,307 9,936
ABO less fair value of plan assets 6,828 7,172
American Airlines, Inc. [Member] | Retiree Medical And Other Postretirement Benefits [Member]    
Defined Benefit Plan Disclosure [Line Items]    
Accumulated postretirement benefit obligation (APBO) 1,010 990
Fair value of plan assets $ 295 $ 266