Components of Accumulated Other Comprehensive Income (Loss), Net of Tax (Parenthetical) (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Accumulated Other Comprehensive Income (Loss) [Line Items]
Increase in prior service credits	$ 331,000,000
Increase in actuarial gains	1,300,000,000
United Airlines, Inc.
Accumulated Other Comprehensive Income (Loss) [Line Items]
Income Tax Expense	6,000,000
Additional (losses) gains related to investments and other	$ 1,000,000	$ 1,000,000	$ (2,000,000)