Earnings (Loss) Per Share - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended			3 Months Ended
	Sep. 30, 2012 UAL 6% Senior Convertible Notes	Sep. 30, 2011 UAL 6% Senior Convertible Notes	Sep. 30, 2012 UAL 6% Senior Convertible Notes	Sep. 30, 2011 UAL 6% Senior Convertible Notes	Sep. 30, 2012 UAL 8% Contingent Senior Notes	Jun. 30, 2011 UAL 4.5% Senior Limited-Subordination Convertible Notes
Earnings Loss Per Share [Line Items]
Debt Outstanding	$ 652		$ 652		$ 125	$ 726
Debt instrument convertible effective interest rate	6.00%	6.00%	6.00%	6.00%	8.00%	4.50%
Due date of debt instruments	2031		2031			2021
Obligated to issue an additional Notes					62.5
Issuance date of additional notes					2013-02
Repurchased debt						$ 570