One-Time Adjustment to Decrease Frequent Flyer Deferred Revenue and Increase Special Revenue (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended	12 Months Ended
	Jun. 30, 2011	Dec. 31, 2011
Special Charges [Line Items]
Special revenue item	$ 107	$ 107
United Air Lines Inc
Special Charges [Line Items]
Special revenue item		88
Continental Airlines Inc
Special Charges [Line Items]
Special revenue item		$ 19