Firm Commitments and Options to Purchase Aircraft (Detail)	Apr. 30, 2013 Embraer EMB175 aircraft Aircraft	Sep. 30, 2013 United Airlines, Inc. Capital Addition Purchase Commitments Airbus A350-1000 aircraft Aircraft	Sep. 30, 2013 United Airlines, Inc. Capital Addition Purchase Commitments Boeing 737 Aircraft	Sep. 30, 2013 United Airlines, Inc. Capital Addition Purchase Commitments Boeing 737 MAX 9 Aircraft Aircraft	Sep. 30, 2013 United Airlines, Inc. Capital Addition Purchase Commitments Boeing 787-8/-9/-10 Aircraft	Sep. 30, 2013 United Airlines, Inc. Capital Addition Purchase Commitments Embraer EMB175 aircraft Aircraft
Commitments [Line Items]
Number of new aircraft committed to purchase	30	35	69	100	58	30