Leases and Capacity Purchase Agreements - Additional Information (Detail) (USD $)	12 Months Ended				1 Months Ended	3 Months Ended		1 Months Ended	12 Months Ended	1 Months Ended
	Dec. 31, 2014		Dec. 31, 2013	Dec. 31, 2012	Apr. 30, 2013 Aircraft	Dec. 31, 2014 Aircraft		May 31, 2013 Aircraft	Dec. 31, 2015 Aircraft	Sep. 30, 2014 Aircraft	Nov. 30, 2013
Operating Leased Assets [Line Items]
Regional capacity purchase expense	$ 2,344,000,000		$ 2,419,000,000	$ 2,470,000,000
Scenario Forecast | Capacity Purchase Agreements
Operating Leased Assets [Line Items]
Scheduled block hours increase (decrease) percentage	10.00%
Change in cash obligation	152,000,000
Cash obligation increase (decrease) percentage	8.00%
United Airlines, Inc.
Operating Leased Assets [Line Items]
Nonaircraft rent expense	1,400,000,000		1,300,000,000	1,300,000,000
Regional capacity purchase expense	2,344,000,000		2,419,000,000	2,470,000,000
United Airlines, Inc. | Revaluation of Liabilities
Operating Leased Assets [Line Items]
Net accretion amounts	160,000,000		173,000,000	240,000,000		160,000,000
United Airlines, Inc. | Variable Interest Entity, Not Primary Beneficiary
Operating Leased Assets [Line Items]
Operating leases obligations	1,500,000,000					1,500,000,000
United Airlines, Inc. | Capacity Purchase Agreements
Operating Leased Assets [Line Items]
Number of aircraft operated	566				30	14
Airline capacity purchase arrangements, expiration year	2029
Number of aircraft purchase					30
United Airlines, Inc. | Regional Aircraft
Operating Leased Assets [Line Items]
Regional capacity purchase expense	442,000,000		428,000,000	463,000,000
United Airlines, Inc. | Minimum
Operating Leased Assets [Line Items]
Lease Fair Value Adjustment, Remaining Lease Term	1 year
United Airlines, Inc. | Maximum
Operating Leased Assets [Line Items]
Lease Fair Value Adjustment, Remaining Lease Term	10 years
SkyWest | Capacity Purchase Agreements
Operating Leased Assets [Line Items]
Number of aircraft operated	19
Number of aircraft to operate								40
SkyWest | Scenario Forecast | Capacity Purchase Agreements
Operating Leased Assets [Line Items]
Number of aircraft operated									21
Aircraft Operating Leases
Operating Leased Assets [Line Items]
Operating leases obligations	7,340,000,000	[1]				7,340,000,000	[1]
Aircraft Operating Leases | Minimum
Operating Leased Assets [Line Items]
Operating lease term	6 years
Operating lease expiration date, in years	2015
Aircraft Operating Leases | Maximum
Operating Leased Assets [Line Items]
Operating lease term	28 years
Operating lease expiration date, in years	2024
Aircraft Operating Leases | United Airlines, Inc.
Operating Leased Assets [Line Items]
Number of aircraft operated										70
Aircraft Operating Leases | United Airlines, Inc. | Embraer E175 Aircraft | New Lease Arrangement
Operating Leased Assets [Line Items]
Number of aircraft operated										50
Aircraft Operating Leases | United Airlines, Inc. | Embraer E175 Aircraft | Extension of Term
Operating Leased Assets [Line Items]
Number of aircraft operated										38
Aircraft Operating Leases | United Airlines, Inc. | Q400 Aircraft
Operating Leased Assets [Line Items]
Number of aircraft operated										31
Facility and Other Operating Leases
Operating Leased Assets [Line Items]
Operating lease extended expiration year	2041
Operating leases obligations	13,022,000,000	[2]				13,022,000,000	[2]
Facility and Other Operating Leases | Denver International Airport
Operating Leased Assets [Line Items]
Operating lease term										10 years
Operating lease original expiration year										2025
Aircraft Leases | United Airlines, Inc. | Embraer E175 Aircraft
Operating Leased Assets [Line Items]
Number of aircraft right to acquire										50
Lease Amendment | United Airlines, Inc.
Operating Leased Assets [Line Items]
Additional investment commitments											$ 450,000,000

[1] The operating lease payments presented above include future payments of $72 million related to 21 nonoperating aircraft as of December 31, 2014.

[2] See Note 17 of this report for additional information related to facility and other operating leases at Hopkins International Airport ("Cleveland").