Schedule of Selected Quarterly Financial Data (Detail) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Selected Quarterly Financial Data [Line Items]
Operating revenue	$ 9,036	$ 10,306	$ 9,914	$ 8,608	$ 9,313	$ 10,563	$ 10,329	$ 8,696	$ 37,864	$ 38,901	$ 38,279	[1]
Income (loss) from operations	1,081	1,899	1,445	741	625	1,191	906	(349)	5,166	2,373	1,249
Net income (loss)	$ 823	$ 4,816	$ 1,193	$ 508	$ 28	$ 924	$ 789	$ (609)	$ 7,340	$ 1,132	$ 571
Basic earnings (loss) per share	$ 2.24	$ 12.83	$ 3.14	$ 1.33	$ 0.08	$ 2.49	$ 2.11	$ (1.66)	$ 19.52	$ 3.05	$ 1.64
Diluted earnings (loss) per share	$ 2.24	$ 12.82	$ 3.14	$ 1.32	$ 0.07	$ 2.37	$ 2.01	$ (1.66)	$ 19.47	$ 2.93	$ 1.53

[1] UAL and United amounts are substantially the same.