Employee Benefit Plans - Fair Values of Retiree Medical and Other Postretirement Benefit Plans Assets by Asset Category (Detail) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Mutual Funds [Member] | International Companies [Member]
Defined Benefit Plan Disclosure [Line Items]
Actual plan asset allocations	27.00%	25.00%
Retiree Medical And Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 295	$ 266	$ 253
Retiree Medical And Other Postretirement Benefits [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	5	266
Retiree Medical And Other Postretirement Benefits [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	290
Retiree Medical And Other Postretirement Benefits [Member] | Money Market Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	5	5
Retiree Medical And Other Postretirement Benefits [Member] | Money Market Funds [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	5	$ 5
Retiree Medical And Other Postretirement Benefits [Member] | Money Market Funds [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 0
Retiree Medical And Other Postretirement Benefits [Member] | Mutual Funds [Member] | International Companies [Member]
Defined Benefit Plan Disclosure [Line Items]
Actual plan asset allocations	30.00%	27.00%
Retiree Medical And Other Postretirement Benefits [Member] | Mutual Funds AAL Class [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 290
Retiree Medical And Other Postretirement Benefits [Member] | Mutual Funds AAL Class [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0
Retiree Medical And Other Postretirement Benefits [Member] | Mutual Funds AAL Class [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 290
Retiree Medical And Other Postretirement Benefits [Member] | Mutual Funds Institutional Class [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		$ 261
Retiree Medical And Other Postretirement Benefits [Member] | Mutual Funds Institutional Class [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		$ 261
American Airlines, Inc. [Member] | Mutual Funds [Member] | International Companies [Member]
Defined Benefit Plan Disclosure [Line Items]
Actual plan asset allocations	30.00%	27.00%
American Airlines, Inc. [Member] | Retiree Medical And Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 295	$ 266	$ 253
American Airlines, Inc. [Member] | Retiree Medical And Other Postretirement Benefits [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	5	266
American Airlines, Inc. [Member] | Retiree Medical And Other Postretirement Benefits [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	290	0
American Airlines, Inc. [Member] | Retiree Medical And Other Postretirement Benefits [Member] | Money Market Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	5	5
American Airlines, Inc. [Member] | Retiree Medical And Other Postretirement Benefits [Member] | Money Market Funds [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	5	5
American Airlines, Inc. [Member] | Retiree Medical And Other Postretirement Benefits [Member] | Money Market Funds [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
American Airlines, Inc. [Member] | Retiree Medical And Other Postretirement Benefits [Member] | Mutual Funds AAL Class [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	290
American Airlines, Inc. [Member] | Retiree Medical And Other Postretirement Benefits [Member] | Mutual Funds AAL Class [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0
American Airlines, Inc. [Member] | Retiree Medical And Other Postretirement Benefits [Member] | Mutual Funds AAL Class [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 290	0
American Airlines, Inc. [Member] | Retiree Medical And Other Postretirement Benefits [Member] | Mutual Funds Institutional Class [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		261
American Airlines, Inc. [Member] | Retiree Medical And Other Postretirement Benefits [Member] | Mutual Funds Institutional Class [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		$ 261