Components of Accumulated Other Comprehensive Income (Loss), Net of Tax (Detail) - USD ($) $ in Millions		3 Months Ended			9 Months Ended
		Sep. 30, 2015	Sep. 30, 2014		Sep. 30, 2015		Sep. 30, 2014
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	[1]	$ (812)	$ 589		$ (1,079)		$ 608
Changes in value	[1]	(116)	(183)	[2]	(144)		(166)	[2]
Amounts reclassified to earnings	[1]	(6)	(18)	[2]	289		(54)	[2]
Comprehensive income (loss) adjustments	[1]	(122)	(201)		145		(220)
Ending Balance	[1]	(934)	388		(934)		388
Pension and Other Postretirement Liabilities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	[1]	(442)	660		(472)		699
Changes in value	[1]	(10)	(66)	[2]	3		(71)	[2]
Amounts reclassified to earnings	[1]	8	(16)	[2]	25		(50)	[2]
Comprehensive income (loss) adjustments	[1]	(2)	(82)		28		(121)
Ending Balance	[1]	(444)	578		(444)		578
Derivative Contracts
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	[1]	(266)	36		(499)		11
Changes in value	[1]	(181)	(120)	[2]	(227)		(99)	[2]
Amounts reclassified to earnings	[1]	150			429		4	[2]
Comprehensive income (loss) adjustments	[1]	(31)	(120)		202		(95)
Ending Balance	[1]	(297)	(84)		(297)		(84)
Investments and Other
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	[1]	11	8		7		13
Changes in value	[1]	(6)	3	[2]	(1)		4	[2]
Amounts reclassified to earnings	[1]		(2)	[2]	(1)		(8)	[2]
Comprehensive income (loss) adjustments	[1]	(6)	1		(2)		(4)
Ending Balance	[1]	5	9		5		9
Pension and Other Postretirement Deferred Taxes
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	[1]	(115)	(115)		(115)		(115)
Changes in value	[1]	(1)			(1)
Amounts reclassified to earnings	[1]	(9)			(9)
Comprehensive income (loss) adjustments	[1]	(10)			(10)
Ending Balance	[1]	(125)	(115)		(125)		(115)
Derivative Contracts Deferred Taxes
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	[1]	0	0		0	[3]	0
Changes in value	[1]	82			82
Amounts reclassified to earnings	[1]	(155)			(155)
Comprehensive income (loss) adjustments	[1]	(73)			(73)
Ending Balance	[1]	$ (73)	$ 0		$ (73)		$ 0

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

[2] Income tax expense for these items was offset by the Company's valuation allowance.

[3] Deferred tax balance was offset by the Company's valuation allowance.