Details about Accumulated Other Comprehensive Income Components (Detail) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Salaries And Related Costs
Accumulated Other Comprehensive Income (Loss) [Line Items]
Amortization of unrecognized losses and prior service cost	[1]	$ 14	$ 6	$ 41	$ 17
Miscellaneous, Net
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassifications of gains into earnings			(2)		(2)
Fuel Oil Contract | Aircraft Fuel
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassifications of losses into earnings			$ 24	$ 2	$ 197

[1] This AOCI component is included in the computation of net periodic pension and other postretirement costs (see Note 5 of this report for additional information).