Financial Instruments And Fair Value Measurements (Activity For Level Three Financial Assets And Financial Liabilities) (Details) (USD $) In Millions	3 Months Ended				9 Months Ended
	Sep. 30, 2011		Sep. 30, 2010		Sep. 30, 2011		Sep. 30, 2010
EETC [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	$ 65	[1]	$ 61	[1]	$ 66	[1]	$ 51	[1]
Settlements	(2)	[1]	(2)	[1]	(4)	[1]	(4)	[1]
Reported in earnings - unrealized		[1]		[1]		[1]		[1]
Reported in other comprehensive income	(3)	[1]	4	[1]	(2)	[1]	16	[1]
Ending Balance	60	[1]	63	[1]	60	[1]	63	[1]
Auction Rate Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	121	[1]			119	[1]
Settlements		[1]
Reported in earnings - unrealized	1	[1]			2	[1]
Reported in other comprehensive income	(1)	[1]
Ending Balance	$ 121	[1]			$ 121	[1]

[1] For 2010, amounts also represent United. For 2011, United's only Level Three recurring measurements are the above EETCs.