Computation of Earnings Per Share (Detail) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
UAL basic earnings (loss) per share:
Net income (loss)	$ 6	$ 653	$ (103)	$ 978
Less: Income allocable to participating securities		(2)		(3)
Earnings (loss) available to common stockholders	6	651	(103)	975
Basic weighted average shares outstanding	331	330	331	329
Earnings (loss) per share, basic	$ 0.02	$ 1.97	$ (0.31)	$ 2.96
UAL diluted earnings (loss) per share:
Earnings (loss) available to common stockholders	6	651	(103)	975
Earnings (loss) available to common stockholders including the effect of dilutive securities	6	663	(103)	1,026
UAL diluted shares outstanding:
Basic weighted average shares outstanding	331	330	331	329
Effect of stock options	1	1		2
Diluted weighted average shares outstanding	332	392	331	396
Earnings (loss) per share, diluted	$ 0.02	$ 1.69	$ (0.31)	$ 2.59
UAL 4.5% Senior Limited-Subordination Convertible Notes
UAL diluted earnings (loss) per share:
Effect of convertible notes on diluted earnings per share, amount		2		31
UAL diluted shares outstanding:
Effect of convertible notes on diluted earnings per share, shares		5		13
UAL potentially dilutive shares excluded from diluted per share amounts:
Potentially dilutive shares excluded from diluted per share amounts	5		5
Continental 4.5% Convertible Notes
UAL diluted earnings (loss) per share:
Effect of convertible notes on diluted earnings per share, amount		2		7
UAL diluted shares outstanding:
Effect of convertible notes on diluted earnings per share, shares		12		12
UAL potentially dilutive shares excluded from diluted per share amounts:
Potentially dilutive shares excluded from diluted per share amounts	12		12
Continental 6% Convertible Junior Subordinated Debentures
UAL diluted earnings (loss) per share:
Effect of convertible notes on diluted earnings per share, amount		4
UAL diluted shares outstanding:
Effect of convertible notes on diluted earnings per share, shares		4
UAL potentially dilutive shares excluded from diluted per share amounts:
Potentially dilutive shares excluded from diluted per share amounts	4		4	4
UAL 6% Senior Convertible Notes
UAL diluted earnings (loss) per share:
Effect of convertible notes on diluted earnings per share, amount		$ 4		$ 13
UAL diluted shares outstanding:
Effect of convertible notes on diluted earnings per share, shares		40		40
UAL potentially dilutive shares excluded from diluted per share amounts:
Potentially dilutive shares excluded from diluted per share amounts	40		40
Restricted Stock And Stock Options
UAL potentially dilutive shares excluded from diluted per share amounts:
Potentially dilutive shares excluded from diluted per share amounts	5	7	6	6