Leases and Capacity Purchase Agreements - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011	Dec. 31, 2010
Operating Leased Assets [Line Items]
Regional capacity purchase expense	$ 2,470,000,000		$ 2,403,000,000	$ 1,812,000,000
Regional Aircraft
Operating Leased Assets [Line Items]
Regional capacity purchase expense	463,000,000		498,000,000	411,000,000
United Air Lines Inc
Operating Leased Assets [Line Items]
Regional capacity purchase expense	1,507,000,000		1,574,000,000	1,610,000,000
United Air Lines Inc | Regional Aircraft
Operating Leased Assets [Line Items]
Regional capacity purchase expense	380,000,000
Continental Airlines Inc | Regional Aircraft
Operating Leased Assets [Line Items]
Regional capacity purchase expense	83,000,000
Capacity Purchase Agreements | United Air Lines Inc
Operating Leased Assets [Line Items]
Number of regional aircraft	275
Airline capacity purchase arrangements, expiration year	2,024
Capacity Purchase Agreements | Continental Airlines Inc
Operating Leased Assets [Line Items]
Number of regional aircraft	276
Airline capacity purchase arrangements, expiration year	2,021
Variable Interest Entity, Not Primary Beneficiary | Tax Exempt Bonds
Operating Leased Assets [Line Items]
Operating leases obligations	1,700,000,000
Variable Interest Entity, Not Primary Beneficiary | United Air Lines Inc | Denver Bonds
Operating Leased Assets [Line Items]
Operating leases obligations	270,000,000
Variable Interest Entity, Not Primary Beneficiary | United Air Lines Inc | Tax Exempt Bonds
Operating Leased Assets [Line Items]
Operating leases obligations	270,000,000
Variable Interest Entity, Not Primary Beneficiary | Continental Airlines Inc | Tax Exempt Bonds
Operating Leased Assets [Line Items]
Operating leases obligations	1,400,000,000
10% increase or decrease in scheduled block hours | Capacity Purchase Agreements | United Air Lines Inc
Operating Leased Assets [Line Items]
Scheduled block hours increase (decrease) percentage	10.00%
Change in cash obligation	76,000,000
Cash obligation increase (decrease) percentage	8.20%
10% increase or decrease in scheduled block hours | Capacity Purchase Agreements | Continental Airlines Inc
Operating Leased Assets [Line Items]
Scheduled block hours increase (decrease) percentage	10.00%
Change in cash obligation	72,000,000
Cash obligation increase (decrease) percentage	8.20%
Minimum
Operating Leased Assets [Line Items]
Projected inflation rate	1.50%
Minimum | United Air Lines Inc
Operating Leased Assets [Line Items]
Lease Fair Value Adjustment, Remaining Lease Term	1 year
Minimum | Continental Airlines Inc
Operating Leased Assets [Line Items]
Lease Fair Value Adjustment, Remaining Lease Term	1 year
Maximum
Operating Leased Assets [Line Items]
Projected inflation rate	2.20%
Maximum | United Air Lines Inc
Operating Leased Assets [Line Items]
Lease Fair Value Adjustment, Remaining Lease Term	12 years
Maximum | Continental Airlines Inc
Operating Leased Assets [Line Items]
Lease Fair Value Adjustment, Remaining Lease Term	12 years
Aircraft Operating Leases
Operating Leased Assets [Line Items]
Operating lease extended expiration year	2032
Operating leases obligations	7,519,000,000	[1]
Aircraft Operating Leases | United Air Lines Inc
Operating Leased Assets [Line Items]
Operating leases obligations	2,297,000,000
Aircraft Operating Leases | Continental Airlines Inc
Operating Leased Assets [Line Items]
Operating leases obligations	$ 5,240,000,000
Aircraft Operating Leases | Minimum
Operating Leased Assets [Line Items]
Operating lease term	1 year
Operating lease expiration date, in years	2013
Aircraft Operating Leases | Maximum
Operating Leased Assets [Line Items]
Operating lease term	26 years
Operating lease expiration date, in years	2024

[1] The operating lease payments presented above include United's and Continental's future payments of $2 million and $128 million, respectively, related to nonoperating aircraft as of December 31, 2012. United and Continental have two and 23 nonoperating aircraft subject to leases, respectively. United's regional carrier, Express Jet, subleases aircraft from Continental; UAL operating lease payments exclude payments related to these aircraft.