Activity for "Level Three" Financial Assets and Financial Liabilities (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Auction Rate Securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	$ 115	$ 112	$ 116	$ 113
Settlements	(9)		(19)
Realized	1		3
Reported in earnings-unrealized		1	1
Reported in other comprehensive income (loss)	(3)	2	3	2
Ending Balance	104	115	104	115
EETC
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	62	63	63	60
Settlements	(2)	(2)	(4)	(5)
Reported in earnings-unrealized				7
Reported in other comprehensive income (loss)	(1)	1
Ending Balance	59	62	59	62
United Airlines, Inc. | Auction Rate Securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	115	112	116	113
Settlements	(9)		(19)
Realized	1		3
Reported in earnings-unrealized		1	1
Reported in other comprehensive income (loss)	(3)	2	3	2
Ending Balance	104	115	104	115
United Airlines, Inc. | EETC
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	62	63	63	60
Settlements	(2)	(2)	(4)	(5)
Reported in earnings-unrealized				7
Reported in other comprehensive income (loss)	(1)	1
Ending Balance	59	62	59	62
United Airlines, Inc. | Convertible Debt Derivative Asset
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	395	289	268	193
Reported in earnings-unrealized	(19)	(87)	108	9
Ending Balance	376	202	376	202
United Airlines, Inc. | Convertible Debt Option Liability
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	(199)	(147)	(128)	(95)
Reported in earnings-unrealized	14	56	(57)	4
Ending Balance	$ (185)	$ (91)	$ (185)	$ (91)