Earnings (Loss) Per Share (Narrative) (Details) (USD $)	12 Months Ended
	Dec. 31, 2011
Earnings Per Share Reconciliation [Line Items]
Principal amount of senior notes	$ 652,000,000
Due date of debt instruments	2031
United 6% Senior Convertible Notes [Member]
Earnings Per Share Reconciliation [Line Items]
Convertible notes interest rate	6.00%
UAL 4.5% Senior Limited Subordination Convertible Notes [Member]
Earnings Per Share Reconciliation [Line Items]
Stock repurchased	570,000,000
Principal amount of senior notes	726,000,000
Convertible notes interest rate	4.50%
Due date of debt instruments	2021
UAL 8% Contingent Senior Notes [Member]
Earnings Per Share Reconciliation [Line Items]
Principal amount of senior notes	$ 125,000,000
Convertible notes interest rate	8.00%