Debt - Additional Information (Detail) (USD $)	3 Months Ended					1 Months Ended	3 Months Ended		12 Months Ended		3 Months Ended		3 Months Ended				3 Months Ended			1 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Feb. 01, 2013 9.875% Senior Notes Due 2013	Feb. 01, 2013 12% Second Lien Due 2013	Feb. 08, 2013 Class B Pass Through Certificates	Oct. 31, 2012 Class A Pass Through Certificates and Class B Pass Through Certificates	Mar. 31, 2013 Class A Pass Through Certificates and Class B Pass Through Certificates	Mar. 31, 2013 Class C Pass Through Certificates	Dec. 31, 2012 Class C Pass Through Certificates	Apr. 01, 2013 Subsequent Event Senior tranche Settlement of Debt	Mar. 31, 2013 LIBOR	Mar. 31, 2013 Certain Market Interest Rates	Mar. 31, 2013 United Airlines, Inc.	Mar. 31, 2012 United Airlines, Inc.	Oct. 31, 2012 United Airlines, Inc. Class B Pass Through Certificates	Oct. 31, 2012 United Airlines, Inc. Class A Pass Through Certificates	Mar. 31, 2013 United Airlines, Inc. Class A Pass Through Certificates and Class B Pass Through Certificates	Mar. 31, 2013 United Airlines, Inc. Class C Pass Through Certificates	Dec. 31, 2012 United Airlines, Inc. Class C Pass Through Certificates	Mar. 27, 2013 Term Loan Facility	Mar. 27, 2013 Revolving Credit Facility	Mar. 27, 2013 Amended Credit Facility
Debt Instrument [Line Items]
Credit Agreement																				$ 900,000,000	$ 1,000,000,000
Debt instrument maturity date																				Apr. 01, 2019	Apr. 01, 2018
Available under revolving credit facility																					1,000,000,000
Debt instrument, floor rate											1.00%
Debt instrument, basis spread on variable rate											3.00%	2.00%
Interest on principal amount	0.25%
Commencement date of installment payment	Jun. 30, 2013
Debt instrument, maturity date	Apr. 01, 2019
Commitment fee percentage	0.75%
Unrestricted liquidity requirement	3,000,000,000
Minimum ratio of appraised value of collateral to the outstanding obligations	1.67
Amount utilized to repay term loan																				900,000,000
Cash utilized to repay term loan																						300,000,000
Aggregate principal amount			400,000,000	200,000,000	123,000,000					180,000,000					132,000,000	712,000,000			425,000,000			1,200,000,000
Debt instrument maturity year			2013	2013	2013					2013												2014
Line of credit maximum borrowing capacity																					500,000,000
Debt instrument stated interest rate			9.875%	12.00%											5.50%	4.00%			6.125%
Proceeds from issuance of long-term debt	$ 109,000,000	$ 86,000,000				$ 844,000,000	$ 201,000,000	$ 54,000,000	$ 425,000,000				$ 109,000,000	$ 86,000,000			$ 494,000,000	$ 331,000,000