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DERIVATIVE INSTRUMENTS - FAIR VALUE OF HEDGE POSITIONS (DETAILS) (USD $)
In Millions, unless otherwise specified
 3 Months Ended
Mar. 31, 2015
Mar. 31, 2014
Derivative [Line Items]    
Net cash received (paid) to for new positions and settlements $ (4)us-gaap_PaymentsForProceedsFromHedgeInvestingActivities $ (7)us-gaap_PaymentsForProceedsFromHedgeInvestingActivities
B737-800 [Member]    
Derivative [Line Items]    
Operating Leases, Number of Units (in Aircraft) 6alk_OperatingLeasesNumberOfUnits
/ us-gaap_AircraftTypeAxis
= us-gaap_B737800Member		  
Not Designated as Hedging Instrument [Member] | Fuel hedge contracts [Member]    
Derivative [Line Items]    
Fuel hedge contracts outstanding (in barrels) 256,000,000invest_DerivativeNonmonetaryNotionalAmount
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_CommodityContractMember
/ us-gaap_HedgingDesignationAxis
= us-gaap_NondesignatedMember