Firm Commitments to Purchase Aircraft (Detail) (United Airlines, Inc., Capital Addition Purchase Commitments)	Dec. 31, 2014 Aircraft
Airbus A350-1000 Aircraft
Commitments [Line Items]
Number of new aircraft committed to purchase	35	[1],[2]
Boeing 737-900ER aircraft
Commitments [Line Items]
Number of new aircraft committed to purchase	34	[1],[2]
Boeing 737 MAX 9 Aircraft
Commitments [Line Items]
Number of new aircraft committed to purchase	100	[1],[2]
Boeing 787-9/-10 Aircraft
Commitments [Line Items]
Number of new aircraft committed to purchase	51	[1],[2]
Embraer E175 Aircraft
Commitments [Line Items]
Number of new aircraft committed to purchase	11	[1],[2]

[1] United also has options and purchase rights for additional aircraft.

[2] United also has committed to purchase two used 737-700 aircraft in 2015.