v2.4.1.9
Derivative Instruments - Put and Call Option Contracts (Details)
 12 Months Ended
Dec. 31, 2014
gal
Dec. 31, 2013
gal
Derivative [Line Items]    
Total fuel price derivative instruments, gallons 47,342,000wex_NotionalAmountOfFuelPriceDerivativesNotDesignatedAsHedgingInstruments [1] 55,880,000wex_NotionalAmountOfFuelPriceDerivativesNotDesignatedAsHedgingInstruments [1]
Unleaded Fuel    
Derivative [Line Items]    
Total fuel price derivative instruments, gallons 31,754,000wex_NotionalAmountOfFuelPriceDerivativesNotDesignatedAsHedgingInstruments
/ wex_FuelPriceDerivativesByTypeOfFuelAxis
= wex_UnleadedFuelMember		 [1] 37,865,000wex_NotionalAmountOfFuelPriceDerivativesNotDesignatedAsHedgingInstruments
/ wex_FuelPriceDerivativesByTypeOfFuelAxis
= wex_UnleadedFuelMember		 [1]
Diesel    
Derivative [Line Items]    
Total fuel price derivative instruments, gallons 15,588,000wex_NotionalAmountOfFuelPriceDerivativesNotDesignatedAsHedgingInstruments
/ wex_FuelPriceDerivativesByTypeOfFuelAxis
= wex_DieselFuelMember		 [1] 18,015,000wex_NotionalAmountOfFuelPriceDerivativesNotDesignatedAsHedgingInstruments
/ wex_FuelPriceDerivativesByTypeOfFuelAxis
= wex_DieselFuelMember		 [1]
[1] The settlement of the put and call option contracts (in all instances, notional amount of puts and calls are equal; strike prices are different) is based upon the New York Mercantile Exchange’s New York Harbor Reformulated Gasoline Blendstock for Oxgenate Blending and the U.S. Department of Energy’s weekly retail on-highway diesel fuel price for the month.