Financial Instruments and Fair Value Measurements - Additional Information (Detail) (USD $) In Millions, unless otherwise specified								9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013 United Airlines, Inc.	Sep. 30, 2012 United Airlines, Inc.	Sep. 30, 2013 6% convertible junior subordinated debentures due 2030	Sep. 30, 2013 Four Point Five Percent Convertible Notes Due Two Thousand Fifteen	Sep. 30, 2013 EETC	Sep. 30, 2013 EETC United Airlines, Inc.	Sep. 30, 2013 Asset-backed Securities United Airlines, Inc. Minimum	Sep. 30, 2013 Asset-backed Securities United Airlines, Inc. Maximum	Sep. 30, 2013 Corporate Debt United Airlines, Inc. Minimum	Sep. 30, 2013 Corporate Debt United Airlines, Inc. Maximum	Sep. 30, 2013 Auction Rate Securities	Sep. 30, 2013 Auction Rate Securities Minimum	Sep. 30, 2013 Auction Rate Securities Maximum	Sep. 30, 2013 Auction Rate Securities United Airlines, Inc. Minimum	Sep. 30, 2013 Auction Rate Securities United Airlines, Inc. Maximum
Fair Value [Line Items]
Available for sale investment, maturity date								2019
Available for sale investment, maturity year									1 year	42 years	1 year	22 years				1 year	33 years
Aggregate principal amount issued													$ 115
Available for sale investment, interest rates reset interval													28 days	7 days	35 days
Investment securities, unrealized gains (losses)							$ 2
Debt instrument convertible stated interest rate	8.00%	8.00%	8.00%	8.00%	6.00%	4.50%
Debt instrument maturity year					2030	2015