Employee Benefit Plans - Components of Net Periodic Benefit Cost (Income) (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Pension Benefits [Member]
Components of net periodic benefit cost:
Service cost	$ 1	$ 1
Interest cost	169	180
Expected return on assets	(226)	(197)
Prior service cost (benefit)	7	7
Unrecognized net loss (gain)	36	36
Net periodic benefit cost (income)	(13)	27
Retiree Medical And Other Postretirement Benefits [Member]
Components of net periodic benefit cost:
Service cost	1	1
Interest cost	9	10
Expected return on assets	(6)	(5)
Prior service cost (benefit)	(59)	(59)
Unrecognized net loss (gain)	(5)	(6)
Net periodic benefit cost (income)	(60)	(59)
American Airlines, Inc. [Member] | Pension Benefits [Member]
Components of net periodic benefit cost:
Service cost	1	0
Interest cost	168	180
Expected return on assets	(225)	(196)
Prior service cost (benefit)	7	7
Unrecognized net loss (gain)	36	36
Net periodic benefit cost (income)	(13)	27
American Airlines, Inc. [Member] | Retiree Medical And Other Postretirement Benefits [Member]
Components of net periodic benefit cost:
Service cost	1	1
Interest cost	9	10
Expected return on assets	(6)	(5)
Prior service cost (benefit)	(59)	(59)
Unrecognized net loss (gain)	(5)	(6)
Net periodic benefit cost (income)	$ (60)	$ (59)