Schedule of Commitments to Purchase Aircrafts (Detail) - United Airlines, Inc. - Capital Addition Purchase Commitments	Sep. 30, 2016 Aircraft	[1]
Airbus A350-1000 Aircraft
Long-term Purchase Commitment [Line Items]
Number of new aircraft committed to purchase	35
Boeing 737NG/737 MAX Aircraft
Long-term Purchase Commitment [Line Items]
Number of new aircraft committed to purchase	172
Boeing 777-300ER Aircraft
Long-term Purchase Commitment [Line Items]
Number of new aircraft committed to purchase	14
Boeing 787-8/-9/-10 Aircraft
Long-term Purchase Commitment [Line Items]
Number of new aircraft committed to purchase	21

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