Valuation and Qualifying Accounts (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011
Allowance for doubtful accounts
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	$ 13		$ 7		$ 6
Additions Charged to Costs and Expenses	35		12		8
Deductions	35	[1]	6	[1]	7	[1]
Balance at End of Period	13		13		7
Obsolescence allowance- spare parts
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	125		89		64
Additions Charged to Costs and Expenses	38		40		31
Deductions	1	[1]	4	[1]	6	[1]
Balance at End of Period	162		125		89
Valuation allowance for deferred tax assets
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	4,603		4,137		4,171
Additions Charged to Costs and Expenses	7		487		333
Deductions	888	[1]	21	[1]	367	[1]
Other	84	[2]
Balance at End of Period	3,806		4,603		4,137
United Airlines, Inc. | Allowance for doubtful accounts
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	13		7		6
Additions Charged to Costs and Expenses	35		12		8
Deductions	35	[1]	6	[1]	7	[1]
Balance at End of Period	13		13		7
United Airlines, Inc. | Obsolescence allowance- spare parts
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	125		89		64
Additions Charged to Costs and Expenses	38		40		31
Deductions	1	[1]	4	[1]	6	[1]
Balance at End of Period	162		125		89
United Airlines, Inc. | Valuation allowance for deferred tax assets
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	4,503		4,048		4,008
Additions Charged to Costs and Expenses	8		661		371
Deductions	898	[1]	206	[1]	331	[1]
Other	163	[2]
Balance at End of Period	$ 3,776		$ 4,503		$ 4,048

[1] Deduction from reserve for purpose for which reserve was created.

[2] See Note 7 to the financial statements included in Part II, Item 8 of this report for additional information related to other valuation allowance adjustments.