Contractual Principal payments (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012
Debt Instrument [Line Items]
2013	$ 1,812
2014	2,120
2015	2,023
2016	985
2017	545
After 2017	4,919
Long term debt	12,404
United Airlines, Inc.
Debt Instrument [Line Items]
2013	1,812
2014	2,120
2015	2,023
2016	985
2017	545
After 2017	4,574
Long term debt	$ 12,059

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Carrying amount of long-term debt, net of unamortized discount or premium, including current and noncurrent amounts. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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