Debt (Narrative) (Details) (USD $)	1 Months Ended	12 Months Ended			12 Months Ended	6 Months Ended	12 Months Ended				3 Months Ended
	Jul. 31, 2011	Dec. 31, 2011	Dec. 31, 2011 6% Senior Convertible Notes Due 2029 [Member]	Dec. 31, 2011 6% Senior Notes Due 2031 [Member]	Dec. 31, 2011 6% Senior Notes Due 2031 [Member] UAL And United [Member]	Jun. 30, 2011 4.5% Senior Limited Subordination Convertible Notes Due 2021 [Member]	Dec. 31, 2011 4.5% Senior Limited Subordination Convertible Notes Due 2021 [Member]	Dec. 31, 2011 4.5% Senior Limited Subordination Convertible Notes Due 2021 [Member] UAL And United [Member]	Dec. 31, 2011 5% Senior Convertible Notes Due 2021 [Member] UAL And United [Member]	Dec. 31, 2011 8% Notes Indenture [Member]	Mar. 31, 2011 5% Senior Convertible Notes Due In 2021 [Member]
Debt Instrument [Line Items]
Debt instrument stated interest rate			6.00%	6.00%				4.50%	5.00%	8.00%	5.00%
Debt instrument maturity year					2031			2021	2021		2021
Conversion price			$ 8.69
Senior convertible notes repurchase period			October 15, 2014, October 15, 2019 and October 15, 2024
Debt instrument period description							UAL common stock only if the closing price of UAL common stock has not been less than 125% of the conversion price for the 60 consecutive trading days immediately prior to the redemption date.
Repayments of senior debt						$ 570,000,000					$ 150,000,000
Principal amount of senior notes		652,000,000		37,000,000		726,000,000				125,000,000
Contingent senior unsecured notes										500,000,000
Number of tranches										eight
Value of tranche										62,500,000
Maximum days for tranche issued										45
Minimum amount of EBITDAR										3,500,000,000
Minimum specified ratio of EBITDAR		1.5 to 1.0
Line of credit facility, maximum borrowing capacity		500,000,000
Required liquidity for revolving credit facility		3,000,000,000
Sale of pre-purchased miles to Chase	$ 165,000,000