Components of Accumulated Other Comprehensive Income (Loss), Net of Tax (Detail) - USD ($) $ in Millions		3 Months Ended			9 Months Ended
		Sep. 30, 2016		Sep. 30, 2015	Sep. 30, 2016		Sep. 30, 2015
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance					$ 8,966
Comprehensive income (loss) adjustments		$ (64)		$ (122)	33		$ 145
Ending Balance		8,439			8,439
Pension and Other Postretirement Liabilities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	[1]	(385)		(442)	(363)		(472)
Changes in value	[1]	(124)		(10)	(157)		3
Amounts reclassified to earnings	[1]	6		8	17		25
Comprehensive income (loss) adjustments	[1]	(118)		(2)	(140)		28
Ending Balance	[1]	(503)		(444)	(503)		(444)
Derivative Contracts | Fuel
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	[1]	(41)		(266)	(215)		(499)
Changes in value	[1]	(6)		(181)	(5)		(227)
Amounts reclassified to earnings	[1]	24		150	197		429
Comprehensive income (loss) adjustments	[1]	18		(31)	192		202
Ending Balance	[1]	(23)		(297)	(23)		(297)
Investments and Other
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	[1]	3		11	3		7
Changes in value	[1]	(2)		(6)	(2)		(1)
Amounts reclassified to earnings	[1]	1			1		(1)
Comprehensive income (loss) adjustments	[1]	(1)		(6)	(1)		(2)
Ending Balance	[1]	2		5	2		5
Pension and Other Postretirement Deferred Taxes
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	[1]	(146)		(115)	(154)		(115)
Changes in value	[1]	45		(1)	57		(1)
Amounts reclassified to earnings	[1]	(2)		(9)	(6)		(9)
Comprehensive income (loss) adjustments	[1]	43		(10)	51		(10)
Ending Balance	[1]	(103)		(125)	(103)		(125)
Derivative Contracts Deferred Taxes | Fuel
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	[1]	(165)			(102)
Changes in value	[1]	2		82	2		82
Amounts reclassified to earnings	[1]	(8)		(155)	(71)		(155)
Comprehensive income (loss) adjustments	[1]	(6)		(73)	(69)		(73)
Ending Balance	[1]	(171)	[2]	(73)	(171)	[2]	(73)
Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	[1]	(734)		(812)	(831)		(1,079)
Changes in value	[1]	(85)		(116)	(105)		(144)
Amounts reclassified to earnings	[1]	21		(6)	138		289
Comprehensive income (loss) adjustments	[1]	(64)		(122)	33		145
Ending Balance	[1]	$ (798)		$ (934)	$ (798)		$ (934)

[1] UAL and United amounts are substantially the same except for an additional gain related to investments and other of $1 million at United for the nine months ended September 30, 2015.

[2] Includes deferred income tax expense of $180 million that will remain in AOCI until all fuel derivatives which are designated for hedge accounting are settled.