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Integration-Related Costs and Special Items - Additional Information (Detail) (USD $)	3 Months Ended									12 Months Ended			1 Months Ended	3 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Jun. 30, 2012 Attendant	Dec. 31, 2014	Dec. 31, 2013 Employee	Dec. 31, 2012	Jan. 31, 2014	Mar. 31, 2012 Attendant
Special Charges [Line Items]
Severance and benefits	$ 141,000,000	$ 6,000,000	$ 38,000,000	$ 14,000,000	$ 91,000,000			$ 14,000,000	$ 76,000,000	$ 199,000,000	$ 105,000,000	$ 125,000,000
Number of positions eliminated									1,300		1,200
Impairment charges of equipment held for disposal										33,000,000
Impairment of indefinite-lived intangible assets, net of tax benefits										10,000,000
Impairment of indefinite-lived intangible assets										16,000,000	1,000,000	30,000,000
Debt instrument principal amount	248,000,000us-gaap_DebtInstrumentCarryingAmount									248,000,000us-gaap_DebtInstrumentCarryingAmount
Debt extinguishment charge	53,000,000			21,000,000						74,000,000		309,000,000
Labor agreement costs						127,000,000us-gaap_OtherLaborRelatedExpenses					127,000,000us-gaap_OtherLaborRelatedExpenses	475,000,000us-gaap_OtherLaborRelatedExpenses
Adjustment of reserves for certain legal matters											29,000,000
Gain related to contract termination											5,000,000us-gaap_GainLossOnContractTermination
Loss on sale of asset											3,000,000us-gaap_GainLossOnDispositionOfAssets
Fair value of liabilities extinguished												212,000,000us-gaap_ExtinguishmentOfDebtAmount
Aircraft-related charges (gains), net	(5,000,000)us-gaap_GainLossOnSaleOfOtherAssets	(9,000,000)us-gaap_GainLossOnSaleOfOtherAssets	(16,000,000)us-gaap_GainLossOnSaleOfOtherAssets	(3,000,000)us-gaap_GainLossOnSaleOfOtherAssets	(1,000,000)us-gaap_GainLossOnSaleOfOtherAssets	(34,000,000)us-gaap_GainLossOnSaleOfOtherAssets	(7,000,000)us-gaap_GainLossOnSaleOfOtherAssets	(8,000,000)us-gaap_GainLossOnSaleOfOtherAssets		(33,000,000)us-gaap_GainLossOnSaleOfOtherAssets	(50,000,000)us-gaap_GainLossOnSaleOfOtherAssets	46,000,000us-gaap_GainLossOnSaleOfOtherAssets
International Association of Machinists
Special Charges [Line Items]
Labor agreement costs											127,000,000
Unsecured Debt
Special Charges [Line Items]
Debt instrument stated interest rate													4.50%
Debt extinguishment charge										74,000,000
Debt instrument maturity year													2021
6% Convertible Junior Subordinated Debentures
Special Charges [Line Items]
Debt instrument stated interest rate	6.00%									6.00%
6% Convertible preferred securities
Special Charges [Line Items]
Debt instrument stated interest rate	6.00%									6.00%
UAL 8% Contingent Senior Notes
Special Charges [Line Items]
Debt instrument stated interest rate												8.00%
Debt instrument convertible effective interest rate												8.00%
Principal amount of senior notes												188,000,000
United Air Lines 8% Senior Notes Due 2024
Special Charges [Line Items]
Debt instrument convertible effective interest rate												8.00%
Principal amount of senior notes												400,000,000
UAL 6% Senior Convertible Notes
Special Charges [Line Items]
Debt instrument stated interest rate	6.00%				6.00%					6.00%	6.00%	6.00%
Debt instrument convertible effective interest rate												6.00%
Principal amount of senior notes												652,000,000
Debt instrument maturity year												2031
United Air Lines 6% Notes Due 2026
Special Charges [Line Items]
Debt instrument stated interest rate	6.00%									6.00%
Debt instrument convertible effective interest rate												6.00%
Principal amount of senior notes												326,000,000
Debt instrument maturity year												2026
United Air Lines 6% Notes Due 2028
Special Charges [Line Items]
Debt instrument stated interest rate	6.00%									6.00%
Debt instrument convertible effective interest rate												6.00%
Principal amount of senior notes												326,000,000
Debt instrument maturity year												2028
Permanently grounded Embraer ERJ 135 aircraft
Special Charges [Line Items]
Costs associated with aircraft			66,000,000							66,000,000
Number of leased aircraft										21
Lease expiry year										2018
Number of aircraft in operation										9
Boeing 737-300 and 737-500 fleets
Special Charges [Line Items]
Impairment charges of equipment held for disposal											32,000,000
Temporarily grounded Boeing 787 aircraft
Special Charges [Line Items]
Costs associated with aircraft											18,000,000
Cleveland [Member]
Special Charges [Line Items]
Severance and benefits										58,000,000
Voluntary early out program
Special Charges [Line Items]
Severance and benefits										141,000,000
Number of positions eliminated										2,500
Voluntary early out program \| Scenario Forecast
Special Charges [Line Items]
Severance and benefits										100,000,000
Voluntary early out program \| Maximum
Special Charges [Line Items]
Severance payment per participant	100,000									100,000
Voluntary retirement program
Special Charges [Line Items]
Severance and benefits											64,000,000			32,000,000
Number of positions eliminated														400
Number of leased aircraft											4
Accruals for future rent					11,000,000						11,000,000
Voluntary leave of absence program
Special Charges [Line Items]
Severance and benefits											26,000,000			17,000,000
Number of positions eliminated														1,800
Involuntary severance programs
Special Charges [Line Items]
Severance and benefits											15,000,000
United Continental Holdings Inc
Special Charges [Line Items]
Labor agreement costs												475,000,000
United Continental Holdings Inc \| Pilot Disability Plan
Special Charges [Line Items]
Labor agreement costs												80,000,000
United Airlines, Inc.
Special Charges [Line Items]
Debt instrument principal amount	11,533,000,000				11,604,000,000					11,533,000,000	11,604,000,000
Aircraft-related charges (gains), net												$ 46,000,000
United Airlines, Inc. \| UAL 8% Contingent Senior Notes
Special Charges [Line Items]
Debt instrument stated interest rate												8.00%
United Airlines, Inc. \| UAL 6% Senior Convertible Notes
Special Charges [Line Items]
Debt instrument stated interest rate	6.00%				6.00%					6.00%	6.00%	6.00%