Details about Accumulated Other Comprehensive Income Components (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013		Mar. 31, 2012
Salaries And Related Costs
Accumulated Other Comprehensive Income [Line Items]
Amortization of unrecognized loss and prior service cost	$ 21	[1]	$ 4	[1],[2]
Salaries And Related Costs | United Airlines, Inc.
Accumulated Other Comprehensive Income [Line Items]
Amortization of unrecognized loss and prior service cost	21	[1]	4	[1],[2]
Income Tax Benefit Expense | United Airlines, Inc.
Accumulated Other Comprehensive Income [Line Items]
Income tax expense on other comprehensive income	6
Fuel Oil Contract | Cash Flow Hedging | Aircraft Fuel
Accumulated Other Comprehensive Income [Line Items]
Fuel contracts-reclassifications of losses into earnings	9	[1]	31	[1]
Fuel Oil Contract | Cash Flow Hedging | Aircraft Fuel | United Airlines, Inc.
Accumulated Other Comprehensive Income [Line Items]
Fuel contracts-reclassifications of losses into earnings	$ 9	[1]	$ 31	[1]

[1] Income tax expense offset by Company's valuation allowance.

[2] This accumulated other comprehensive income component is included in the computation of net periodic pension costs (see Note 5 of this report for additional details.)