Computation of Earnings Per Share (Detail) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
UAL basic earnings (loss) per share:
Net income (loss)	$ 339	$ 538	$ (109)	$ 325
Less: Income allocable to participating securities	(1)	(2)		(1)
Earnings (loss) available to common stockholders	338	536	(109)	324
Basic weighted average shares outstanding	331	330	331	329
Earnings (loss) per share, basic	$ 1.02	$ 1.63	$ (0.33)	$ 0.98
UAL diluted earnings (loss) per share:
Earnings (loss) available to common stockholders	338	536	(109)	324
Earnings (loss) available to common stockholders including the effect of dilutive securities	349	558	(109)	337
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	393	400	331	383
Earnings (loss) per share, diluted	$ 0.89	$ 1.39	$ (0.33)	$ 0.88
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	11
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	18
Continental 4.5% Convertible Notes
UAL diluted earnings (loss) per share:
Effect of convertible notes on diluted earnings per share, amount	2	2		4
UAL diluted shares outstanding:
Effect of convertible notes on diluted earnings per share, shares	12	12		12
UAL potentially dilutive shares excluded from diluted per share amounts:
Potentially dilutive shares excluded from diluted per share amounts			12
Continental 6% Convertible Junior Subordinated Debentures
UAL diluted earnings (loss) per share:
Effect of convertible notes on diluted earnings per share, amount	3	4
UAL diluted shares outstanding:
Effect of convertible notes on diluted earnings per share, shares	4	4
UAL potentially dilutive shares excluded from diluted per share amounts:
Potentially dilutive shares excluded from diluted per share amounts			4	4
UAL 6% Senior Convertible Notes
UAL diluted earnings (loss) per share:
Effect of convertible notes on diluted earnings per share, amount	$ 4	$ 5		$ 9
UAL diluted shares outstanding:
Effect of convertible notes on diluted earnings per share, shares	40	40		40
UAL potentially dilutive shares excluded from diluted per share amounts:
Potentially dilutive shares excluded from diluted per share amounts			40
Restricted Stock And Units And Stock Options
UAL potentially dilutive shares excluded from diluted per share amounts:
Potentially dilutive shares excluded from diluted per share amounts	5	7	7	6