Operating Revenue by Principle Geographic Region (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Segment Reporting Information [Line Items]
Total revenues	$ 9,313	$ 10,563	$ 10,329	$ 8,696	$ 9,329	$ 10,228	$ 10,001	$ 8,721	$ 38,901	$ 38,279	$ 37,152
Domestic (U.S. and Canada)
Segment Reporting Information [Line Items]
Total revenues									22,320	22,092	21,276
Pacific
Segment Reporting Information [Line Items]
Total revenues									5,767	5,794	6,040
Atlantic
Segment Reporting Information [Line Items]
Total revenues									7,321	7,132	6,582
Latin America
Segment Reporting Information [Line Items]
Total revenues									3,493	3,261	3,254
United Airlines, Inc.
Segment Reporting Information [Line Items]
Total revenues									38,901	38,287	37,160
United Airlines, Inc. | Domestic (U.S. and Canada)
Segment Reporting Information [Line Items]
Total revenues									22,320	22,100	21,284
United Airlines, Inc. | Pacific
Segment Reporting Information [Line Items]
Total revenues									5,767	5,794	6,040
United Airlines, Inc. | Atlantic
Segment Reporting Information [Line Items]
Total revenues									7,321	7,132	6,582
United Airlines, Inc. | Latin America
Segment Reporting Information [Line Items]
Total revenues									$ 3,493	$ 3,261	$ 3,254