Details about Accumulated Other Comprehensive Income Components (Detail) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Salaries And Related Costs
Accumulated Other Comprehensive Income (Loss) [Line Items]
Amortization of unrecognized losses and prior service cost (credit)	[1]	$ 6	$ 8	$ 17	$ 25
Miscellaneous, Net
Accumulated Other Comprehensive Income (Loss) [Line Items]
Available-for-sale securities-reclassifications of gains into earnings		1		1	(1)
Fuel Oil Contract | Aircraft Fuel
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassifications of losses into earnings		$ 24	$ 150	$ 197	$ 429

[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).