v2.4.1.9
Derivative Instruments - Fair Value Of Fuel Price Derivative Instruments In Consolidated Balance Sheet (Details) (USD $)
In Thousands, unless otherwise specified
Dec. 31, 2014
gal
Dec. 31, 2013
gal
Derivatives, Fair Value [Line Items]    
Total fuel price derivative instruments, Aggregate Notional (gallons) 47,342,000invest_DerivativeNonmonetaryNotionalAmount [1] 55,880,000invest_DerivativeNonmonetaryNotionalAmount
Total fuel price derivative instruments, Fair Value $ 40,969us-gaap_DerivativeFairValueOfDerivativeNet $ (7,358)us-gaap_DerivativeFairValueOfDerivativeNet
Unleaded Fuel    
Derivatives, Fair Value [Line Items]    
Total fuel price derivative instruments, Aggregate Notional (gallons) 31,754,000invest_DerivativeNonmonetaryNotionalAmount
/ wex_FuelPriceDerivativesByTypeOfFuelAxis
= wex_UnleadedFuelMember		 [1] 37,865,000invest_DerivativeNonmonetaryNotionalAmount
/ wex_FuelPriceDerivativesByTypeOfFuelAxis
= wex_UnleadedFuelMember
Total fuel price derivative instruments, Fair Value 29,120us-gaap_DerivativeFairValueOfDerivativeNet
/ wex_FuelPriceDerivativesByTypeOfFuelAxis
= wex_UnleadedFuelMember		 (5,216)us-gaap_DerivativeFairValueOfDerivativeNet
/ wex_FuelPriceDerivativesByTypeOfFuelAxis
= wex_UnleadedFuelMember
Unleaded Fuel | Options settling July 2015 – March 2016    
Derivatives, Fair Value [Line Items]    
Total fuel price derivative instruments, Aggregate Notional (gallons) 7,873,000invest_DerivativeNonmonetaryNotionalAmount
/ us-gaap_DerivativeInstrumentRiskAxis
= wex_OptionsSettlingJulyTwoThousandThirteenToMarchTwoThousandFourteenMember
/ wex_FuelPriceDerivativesByTypeOfFuelAxis
= wex_UnleadedFuelMember		 [1]  
Total fuel price derivative instruments, Fair Value 6,459us-gaap_DerivativeFairValueOfDerivativeNet
/ us-gaap_DerivativeInstrumentRiskAxis
= wex_OptionsSettlingJulyTwoThousandThirteenToMarchTwoThousandFourteenMember
/ wex_FuelPriceDerivativesByTypeOfFuelAxis
= wex_UnleadedFuelMember		  
Unleaded Fuel | Options settling April 2015 – December 2015    
Derivatives, Fair Value [Line Items]    
Total fuel price derivative instruments, Aggregate Notional (gallons) 7,562,000invest_DerivativeNonmonetaryNotionalAmount
/ us-gaap_DerivativeInstrumentRiskAxis
= wex_OptionsSettlingAprilTwoThousandThirteenToDecemberTwoThousandThirteenMember
/ wex_FuelPriceDerivativesByTypeOfFuelAxis
= wex_UnleadedFuelMember		 [1]  
Total fuel price derivative instruments, Fair Value 7,109us-gaap_DerivativeFairValueOfDerivativeNet
/ us-gaap_DerivativeInstrumentRiskAxis
= wex_OptionsSettlingAprilTwoThousandThirteenToDecemberTwoThousandThirteenMember
/ wex_FuelPriceDerivativesByTypeOfFuelAxis
= wex_UnleadedFuelMember		  
Unleaded Fuel | Options settling January 2015 – September 2015    
Derivatives, Fair Value [Line Items]    
Total fuel price derivative instruments, Aggregate Notional (gallons) 8,689,000invest_DerivativeNonmonetaryNotionalAmount
/ us-gaap_DerivativeInstrumentRiskAxis
= wex_OptionsSettlingJanuaryTwoThousandThirteenToSeptemberTwoThousandThirteenMember
/ wex_FuelPriceDerivativesByTypeOfFuelAxis
= wex_UnleadedFuelMember		 [1]  
Total fuel price derivative instruments, Fair Value 8,369us-gaap_DerivativeFairValueOfDerivativeNet
/ us-gaap_DerivativeInstrumentRiskAxis
= wex_OptionsSettlingJanuaryTwoThousandThirteenToSeptemberTwoThousandThirteenMember
/ wex_FuelPriceDerivativesByTypeOfFuelAxis
= wex_UnleadedFuelMember		  
Unleaded Fuel | Options settling October 2014 – June 2015    
Derivatives, Fair Value [Line Items]    
Total fuel price derivative instruments, Aggregate Notional (gallons) 5,151,000invest_DerivativeNonmonetaryNotionalAmount
/ us-gaap_DerivativeInstrumentRiskAxis
= wex_OptionsSettlingOctoberTwoThousandTwelveToJuneTwoThousandThirteenMember
/ wex_FuelPriceDerivativesByTypeOfFuelAxis
= wex_UnleadedFuelMember		 [1] 7,582,000invest_DerivativeNonmonetaryNotionalAmount
/ us-gaap_DerivativeInstrumentRiskAxis
= wex_OptionsSettlingOctoberTwoThousandTwelveToJuneTwoThousandThirteenMember
/ wex_FuelPriceDerivativesByTypeOfFuelAxis
= wex_UnleadedFuelMember
Total fuel price derivative instruments, Fair Value 4,772us-gaap_DerivativeFairValueOfDerivativeNet
/ us-gaap_DerivativeInstrumentRiskAxis
= wex_OptionsSettlingOctoberTwoThousandTwelveToJuneTwoThousandThirteenMember
/ wex_FuelPriceDerivativesByTypeOfFuelAxis
= wex_UnleadedFuelMember		 (481)us-gaap_DerivativeFairValueOfDerivativeNet
/ us-gaap_DerivativeInstrumentRiskAxis
= wex_OptionsSettlingOctoberTwoThousandTwelveToJuneTwoThousandThirteenMember
/ wex_FuelPriceDerivativesByTypeOfFuelAxis
= wex_UnleadedFuelMember
Unleaded Fuel | Options settling July 2014 – March 2015    
Derivatives, Fair Value [Line Items]    
Total fuel price derivative instruments, Aggregate Notional (gallons) 2,479,000invest_DerivativeNonmonetaryNotionalAmount
/ us-gaap_DerivativeInstrumentRiskAxis
= wex_OptionsSettlingJulyTwoThousandTwelveToMarchTwoThousandThirteenMember
/ wex_FuelPriceDerivativesByTypeOfFuelAxis
= wex_UnleadedFuelMember		 [1] 7,732,000invest_DerivativeNonmonetaryNotionalAmount
/ us-gaap_DerivativeInstrumentRiskAxis
= wex_OptionsSettlingJulyTwoThousandTwelveToMarchTwoThousandThirteenMember
/ wex_FuelPriceDerivativesByTypeOfFuelAxis
= wex_UnleadedFuelMember
Total fuel price derivative instruments, Fair Value 2,411us-gaap_DerivativeFairValueOfDerivativeNet
/ us-gaap_DerivativeInstrumentRiskAxis
= wex_OptionsSettlingJulyTwoThousandTwelveToMarchTwoThousandThirteenMember
/ wex_FuelPriceDerivativesByTypeOfFuelAxis
= wex_UnleadedFuelMember		 (1,076)us-gaap_DerivativeFairValueOfDerivativeNet
/ us-gaap_DerivativeInstrumentRiskAxis
= wex_OptionsSettlingJulyTwoThousandTwelveToMarchTwoThousandThirteenMember
/ wex_FuelPriceDerivativesByTypeOfFuelAxis
= wex_UnleadedFuelMember
Unleaded Fuel | Options settling April 2014 – December 2014    
Derivatives, Fair Value [Line Items]    
Total fuel price derivative instruments, Aggregate Notional (gallons)   7,861,000invest_DerivativeNonmonetaryNotionalAmount
/ us-gaap_DerivativeInstrumentRiskAxis
= wex_OptionsSettlingAprilTwoThousandTwelveToDecemberTwoThousandTwelveMember
/ wex_FuelPriceDerivativesByTypeOfFuelAxis
= wex_UnleadedFuelMember
Total fuel price derivative instruments, Fair Value   (1,051)us-gaap_DerivativeFairValueOfDerivativeNet
/ us-gaap_DerivativeInstrumentRiskAxis
= wex_OptionsSettlingAprilTwoThousandTwelveToDecemberTwoThousandTwelveMember
/ wex_FuelPriceDerivativesByTypeOfFuelAxis
= wex_UnleadedFuelMember
Unleaded Fuel | Options settling January 2014– September 2014    
Derivatives, Fair Value [Line Items]    
Total fuel price derivative instruments, Aggregate Notional (gallons)   8,182,000invest_DerivativeNonmonetaryNotionalAmount
/ us-gaap_DerivativeInstrumentRiskAxis
= wex_OptionsSettlingJanuaryTwoThousandTwelveToSeptemberTwoThousandTwelveMember
/ wex_FuelPriceDerivativesByTypeOfFuelAxis
= wex_UnleadedFuelMember
Total fuel price derivative instruments, Fair Value   (911)us-gaap_DerivativeFairValueOfDerivativeNet
/ us-gaap_DerivativeInstrumentRiskAxis
= wex_OptionsSettlingJanuaryTwoThousandTwelveToSeptemberTwoThousandTwelveMember
/ wex_FuelPriceDerivativesByTypeOfFuelAxis
= wex_UnleadedFuelMember
Unleaded Fuel | Options settling October 2013 – June 2014    
Derivatives, Fair Value [Line Items]    
Total fuel price derivative instruments, Aggregate Notional (gallons)   4,144,000invest_DerivativeNonmonetaryNotionalAmount
/ us-gaap_DerivativeInstrumentRiskAxis
= wex_OptionsSettlingOctoberTwoThousandElevenToJuneTwoThousandTwelveMember
/ wex_FuelPriceDerivativesByTypeOfFuelAxis
= wex_UnleadedFuelMember
Total fuel price derivative instruments, Fair Value   (1,407)us-gaap_DerivativeFairValueOfDerivativeNet
/ us-gaap_DerivativeInstrumentRiskAxis
= wex_OptionsSettlingOctoberTwoThousandElevenToJuneTwoThousandTwelveMember
/ wex_FuelPriceDerivativesByTypeOfFuelAxis
= wex_UnleadedFuelMember
Unleaded Fuel | Options settling July 2013 – March 2014    
Derivatives, Fair Value [Line Items]    
Total fuel price derivative instruments, Aggregate Notional (gallons)   2,364,000invest_DerivativeNonmonetaryNotionalAmount
/ us-gaap_DerivativeInstrumentRiskAxis
= wex_OptionsSettlingJulyTwoThousandElevenToMarchTwoThousandTwelveMember
/ wex_FuelPriceDerivativesByTypeOfFuelAxis
= wex_UnleadedFuelMember
Total fuel price derivative instruments, Fair Value   (290)us-gaap_DerivativeFairValueOfDerivativeNet
/ us-gaap_DerivativeInstrumentRiskAxis
= wex_OptionsSettlingJulyTwoThousandElevenToMarchTwoThousandTwelveMember
/ wex_FuelPriceDerivativesByTypeOfFuelAxis
= wex_UnleadedFuelMember
Diesel    
Derivatives, Fair Value [Line Items]    
Total fuel price derivative instruments, Aggregate Notional (gallons) 15,588,000invest_DerivativeNonmonetaryNotionalAmount
/ wex_FuelPriceDerivativesByTypeOfFuelAxis
= wex_DieselFuelMember		 [1] 18,015,000invest_DerivativeNonmonetaryNotionalAmount
/ wex_FuelPriceDerivativesByTypeOfFuelAxis
= wex_DieselFuelMember
Total fuel price derivative instruments, Fair Value 11,849us-gaap_DerivativeFairValueOfDerivativeNet
/ wex_FuelPriceDerivativesByTypeOfFuelAxis
= wex_DieselFuelMember		 (2,142)us-gaap_DerivativeFairValueOfDerivativeNet
/ wex_FuelPriceDerivativesByTypeOfFuelAxis
= wex_DieselFuelMember
Diesel | Options settling July 2015 – March 2016    
Derivatives, Fair Value [Line Items]    
Total fuel price derivative instruments, Aggregate Notional (gallons) 3,951,000invest_DerivativeNonmonetaryNotionalAmount
/ us-gaap_DerivativeInstrumentRiskAxis
= wex_OptionsSettlingJulyTwoThousandThirteenToMarchTwoThousandFourteenMember
/ wex_FuelPriceDerivativesByTypeOfFuelAxis
= wex_DieselFuelMember		 [1]  
Total fuel price derivative instruments, Fair Value 2,842us-gaap_DerivativeFairValueOfDerivativeNet
/ us-gaap_DerivativeInstrumentRiskAxis
= wex_OptionsSettlingJulyTwoThousandThirteenToMarchTwoThousandFourteenMember
/ wex_FuelPriceDerivativesByTypeOfFuelAxis
= wex_DieselFuelMember		  
Diesel | Options settling April 2015 – December 2015    
Derivatives, Fair Value [Line Items]    
Total fuel price derivative instruments, Aggregate Notional (gallons) 3,708,000invest_DerivativeNonmonetaryNotionalAmount
/ us-gaap_DerivativeInstrumentRiskAxis
= wex_OptionsSettlingAprilTwoThousandThirteenToDecemberTwoThousandThirteenMember
/ wex_FuelPriceDerivativesByTypeOfFuelAxis
= wex_DieselFuelMember		 [1]  
Total fuel price derivative instruments, Fair Value 2,720us-gaap_DerivativeFairValueOfDerivativeNet
/ us-gaap_DerivativeInstrumentRiskAxis
= wex_OptionsSettlingAprilTwoThousandThirteenToDecemberTwoThousandThirteenMember
/ wex_FuelPriceDerivativesByTypeOfFuelAxis
= wex_DieselFuelMember		  
Diesel | Options settling January 2015 – September 2015    
Derivatives, Fair Value [Line Items]    
Total fuel price derivative instruments, Aggregate Notional (gallons) 4,300,000invest_DerivativeNonmonetaryNotionalAmount
/ us-gaap_DerivativeInstrumentRiskAxis
= wex_OptionsSettlingJanuaryTwoThousandThirteenToSeptemberTwoThousandThirteenMember
/ wex_FuelPriceDerivativesByTypeOfFuelAxis
= wex_DieselFuelMember		 [1]  
Total fuel price derivative instruments, Fair Value 3,464us-gaap_DerivativeFairValueOfDerivativeNet
/ us-gaap_DerivativeInstrumentRiskAxis
= wex_OptionsSettlingJanuaryTwoThousandThirteenToSeptemberTwoThousandThirteenMember
/ wex_FuelPriceDerivativesByTypeOfFuelAxis
= wex_DieselFuelMember		  
Diesel | Options settling October 2014 – June 2015    
Derivatives, Fair Value [Line Items]    
Total fuel price derivative instruments, Aggregate Notional (gallons) 2,451,000invest_DerivativeNonmonetaryNotionalAmount
/ us-gaap_DerivativeInstrumentRiskAxis
= wex_OptionsSettlingOctoberTwoThousandTwelveToJuneTwoThousandThirteenMember
/ wex_FuelPriceDerivativesByTypeOfFuelAxis
= wex_DieselFuelMember		 [1] 3,609,000invest_DerivativeNonmonetaryNotionalAmount
/ us-gaap_DerivativeInstrumentRiskAxis
= wex_OptionsSettlingOctoberTwoThousandTwelveToJuneTwoThousandThirteenMember
/ wex_FuelPriceDerivativesByTypeOfFuelAxis
= wex_DieselFuelMember
Total fuel price derivative instruments, Fair Value 1,906us-gaap_DerivativeFairValueOfDerivativeNet
/ us-gaap_DerivativeInstrumentRiskAxis
= wex_OptionsSettlingOctoberTwoThousandTwelveToJuneTwoThousandThirteenMember
/ wex_FuelPriceDerivativesByTypeOfFuelAxis
= wex_DieselFuelMember		 (318)us-gaap_DerivativeFairValueOfDerivativeNet
/ us-gaap_DerivativeInstrumentRiskAxis
= wex_OptionsSettlingOctoberTwoThousandTwelveToJuneTwoThousandThirteenMember
/ wex_FuelPriceDerivativesByTypeOfFuelAxis
= wex_DieselFuelMember
Diesel | Options settling July 2014 – March 2015    
Derivatives, Fair Value [Line Items]    
Total fuel price derivative instruments, Aggregate Notional (gallons) 1,178,000invest_DerivativeNonmonetaryNotionalAmount
/ us-gaap_DerivativeInstrumentRiskAxis
= wex_OptionsSettlingJulyTwoThousandTwelveToMarchTwoThousandThirteenMember
/ wex_FuelPriceDerivativesByTypeOfFuelAxis
= wex_DieselFuelMember		 [1] 3,691,000invest_DerivativeNonmonetaryNotionalAmount
/ us-gaap_DerivativeInstrumentRiskAxis
= wex_OptionsSettlingJulyTwoThousandTwelveToMarchTwoThousandThirteenMember
/ wex_FuelPriceDerivativesByTypeOfFuelAxis
= wex_DieselFuelMember
Total fuel price derivative instruments, Fair Value 917us-gaap_DerivativeFairValueOfDerivativeNet
/ us-gaap_DerivativeInstrumentRiskAxis
= wex_OptionsSettlingJulyTwoThousandTwelveToMarchTwoThousandThirteenMember
/ wex_FuelPriceDerivativesByTypeOfFuelAxis
= wex_DieselFuelMember		 (385)us-gaap_DerivativeFairValueOfDerivativeNet
/ us-gaap_DerivativeInstrumentRiskAxis
= wex_OptionsSettlingJulyTwoThousandTwelveToMarchTwoThousandThirteenMember
/ wex_FuelPriceDerivativesByTypeOfFuelAxis
= wex_DieselFuelMember
Diesel | Options settling April 2014 – December 2014    
Derivatives, Fair Value [Line Items]    
Total fuel price derivative instruments, Aggregate Notional (gallons)   3,745,000invest_DerivativeNonmonetaryNotionalAmount
/ us-gaap_DerivativeInstrumentRiskAxis
= wex_OptionsSettlingAprilTwoThousandTwelveToDecemberTwoThousandTwelveMember
/ wex_FuelPriceDerivativesByTypeOfFuelAxis
= wex_DieselFuelMember
Total fuel price derivative instruments, Fair Value   (436)us-gaap_DerivativeFairValueOfDerivativeNet
/ us-gaap_DerivativeInstrumentRiskAxis
= wex_OptionsSettlingAprilTwoThousandTwelveToDecemberTwoThousandTwelveMember
/ wex_FuelPriceDerivativesByTypeOfFuelAxis
= wex_DieselFuelMember
Diesel | Options settling January 2014– September 2014    
Derivatives, Fair Value [Line Items]    
Total fuel price derivative instruments, Aggregate Notional (gallons)   4,046,000invest_DerivativeNonmonetaryNotionalAmount
/ us-gaap_DerivativeInstrumentRiskAxis
= wex_OptionsSettlingJanuaryTwoThousandTwelveToSeptemberTwoThousandTwelveMember
/ wex_FuelPriceDerivativesByTypeOfFuelAxis
= wex_DieselFuelMember
Total fuel price derivative instruments, Fair Value   (516)us-gaap_DerivativeFairValueOfDerivativeNet
/ us-gaap_DerivativeInstrumentRiskAxis
= wex_OptionsSettlingJanuaryTwoThousandTwelveToSeptemberTwoThousandTwelveMember
/ wex_FuelPriceDerivativesByTypeOfFuelAxis
= wex_DieselFuelMember
Diesel | Options settling October 2013 – June 2014    
Derivatives, Fair Value [Line Items]    
Total fuel price derivative instruments, Aggregate Notional (gallons)   1,862,000invest_DerivativeNonmonetaryNotionalAmount
/ us-gaap_DerivativeInstrumentRiskAxis
= wex_OptionsSettlingOctoberTwoThousandElevenToJuneTwoThousandTwelveMember
/ wex_FuelPriceDerivativesByTypeOfFuelAxis
= wex_DieselFuelMember
Total fuel price derivative instruments, Fair Value   (413)us-gaap_DerivativeFairValueOfDerivativeNet
/ us-gaap_DerivativeInstrumentRiskAxis
= wex_OptionsSettlingOctoberTwoThousandElevenToJuneTwoThousandTwelveMember
/ wex_FuelPriceDerivativesByTypeOfFuelAxis
= wex_DieselFuelMember
Diesel | Options settling July 2013 – March 2014    
Derivatives, Fair Value [Line Items]    
Total fuel price derivative instruments, Aggregate Notional (gallons)   1,062,000invest_DerivativeNonmonetaryNotionalAmount
/ us-gaap_DerivativeInstrumentRiskAxis
= wex_OptionsSettlingJulyTwoThousandElevenToMarchTwoThousandTwelveMember
/ wex_FuelPriceDerivativesByTypeOfFuelAxis
= wex_DieselFuelMember
Total fuel price derivative instruments, Fair Value   $ (74)us-gaap_DerivativeFairValueOfDerivativeNet
/ us-gaap_DerivativeInstrumentRiskAxis
= wex_OptionsSettlingJulyTwoThousandElevenToMarchTwoThousandTwelveMember
/ wex_FuelPriceDerivativesByTypeOfFuelAxis
= wex_DieselFuelMember
Put Option | Unleaded Fuel | Options settling July 2015 – March 2016    
Derivatives, Fair Value [Line Items]    
Total fuel price derivative instruments, Strike Price of Underlying (per gallon) 2.483us-gaap_DerivativePriceRiskOptionStrikePrice
/ us-gaap_DerivativeByNatureAxis
= us-gaap_PutOptionMember
/ us-gaap_DerivativeInstrumentRiskAxis
= wex_OptionsSettlingJulyTwoThousandThirteenToMarchTwoThousandFourteenMember
/ wex_FuelPriceDerivativesByTypeOfFuelAxis
= wex_UnleadedFuelMember		 [2]  
Put Option | Unleaded Fuel | Options settling April 2015 – December 2015    
Derivatives, Fair Value [Line Items]    
Total fuel price derivative instruments, Strike Price of Underlying (per gallon) 2.620us-gaap_DerivativePriceRiskOptionStrikePrice
/ us-gaap_DerivativeByNatureAxis
= us-gaap_PutOptionMember
/ us-gaap_DerivativeInstrumentRiskAxis
= wex_OptionsSettlingAprilTwoThousandThirteenToDecemberTwoThousandThirteenMember
/ wex_FuelPriceDerivativesByTypeOfFuelAxis
= wex_UnleadedFuelMember		 [2]  
Put Option | Unleaded Fuel | Options settling January 2015 – September 2015    
Derivatives, Fair Value [Line Items]    
Total fuel price derivative instruments, Strike Price of Underlying (per gallon) 2.625us-gaap_DerivativePriceRiskOptionStrikePrice
/ us-gaap_DerivativeByNatureAxis
= us-gaap_PutOptionMember
/ us-gaap_DerivativeInstrumentRiskAxis
= wex_OptionsSettlingJanuaryTwoThousandThirteenToSeptemberTwoThousandThirteenMember
/ wex_FuelPriceDerivativesByTypeOfFuelAxis
= wex_UnleadedFuelMember		 [2]  
Put Option | Unleaded Fuel | Options settling October 2014 – June 2015    
Derivatives, Fair Value [Line Items]    
Total fuel price derivative instruments, Strike Price of Underlying (per gallon) 2.568us-gaap_DerivativePriceRiskOptionStrikePrice
/ us-gaap_DerivativeByNatureAxis
= us-gaap_PutOptionMember
/ us-gaap_DerivativeInstrumentRiskAxis
= wex_OptionsSettlingOctoberTwoThousandTwelveToJuneTwoThousandThirteenMember
/ wex_FuelPriceDerivativesByTypeOfFuelAxis
= wex_UnleadedFuelMember		 [2]  
Put Option | Unleaded Fuel | Options settling July 2014 – March 2015    
Derivatives, Fair Value [Line Items]    
Total fuel price derivative instruments, Strike Price of Underlying (per gallon) 2.510us-gaap_DerivativePriceRiskOptionStrikePrice
/ us-gaap_DerivativeByNatureAxis
= us-gaap_PutOptionMember
/ us-gaap_DerivativeInstrumentRiskAxis
= wex_OptionsSettlingJulyTwoThousandTwelveToMarchTwoThousandThirteenMember
/ wex_FuelPriceDerivativesByTypeOfFuelAxis
= wex_UnleadedFuelMember		 [2]  
Put Option | Unleaded Fuel | Options settling April 2014 – December 2014    
Derivatives, Fair Value [Line Items]    
Total fuel price derivative instruments, Strike Price of Underlying (per gallon) 2.615us-gaap_DerivativePriceRiskOptionStrikePrice
/ us-gaap_DerivativeByNatureAxis
= us-gaap_PutOptionMember
/ us-gaap_DerivativeInstrumentRiskAxis
= wex_OptionsSettlingAprilTwoThousandTwelveToDecemberTwoThousandTwelveMember
/ wex_FuelPriceDerivativesByTypeOfFuelAxis
= wex_UnleadedFuelMember		 [2]  
Put Option | Unleaded Fuel | Options settling January 2014– September 2014    
Derivatives, Fair Value [Line Items]    
Total fuel price derivative instruments, Strike Price of Underlying (per gallon) 2.700us-gaap_DerivativePriceRiskOptionStrikePrice
/ us-gaap_DerivativeByNatureAxis
= us-gaap_PutOptionMember
/ us-gaap_DerivativeInstrumentRiskAxis
= wex_OptionsSettlingJanuaryTwoThousandTwelveToSeptemberTwoThousandTwelveMember
/ wex_FuelPriceDerivativesByTypeOfFuelAxis
= wex_UnleadedFuelMember		 [2]  
Put Option | Unleaded Fuel | Options settling October 2013 – June 2014    
Derivatives, Fair Value [Line Items]    
Total fuel price derivative instruments, Strike Price of Underlying (per gallon) 2.485us-gaap_DerivativePriceRiskOptionStrikePrice
/ us-gaap_DerivativeByNatureAxis
= us-gaap_PutOptionMember
/ us-gaap_DerivativeInstrumentRiskAxis
= wex_OptionsSettlingOctoberTwoThousandElevenToJuneTwoThousandTwelveMember
/ wex_FuelPriceDerivativesByTypeOfFuelAxis
= wex_UnleadedFuelMember		 [2]  
Put Option | Unleaded Fuel | Options settling July 2013 – March 2014    
Derivatives, Fair Value [Line Items]    
Total fuel price derivative instruments, Strike Price of Underlying (per gallon) 2.633us-gaap_DerivativePriceRiskOptionStrikePrice
/ us-gaap_DerivativeByNatureAxis
= us-gaap_PutOptionMember
/ us-gaap_DerivativeInstrumentRiskAxis
= wex_OptionsSettlingJulyTwoThousandElevenToMarchTwoThousandTwelveMember
/ wex_FuelPriceDerivativesByTypeOfFuelAxis
= wex_UnleadedFuelMember		 [2]  
Put Option | Diesel | Options settling July 2015 – March 2016    
Derivatives, Fair Value [Line Items]    
Total fuel price derivative instruments, Strike Price of Underlying (per gallon) 3.724us-gaap_DerivativePriceRiskOptionStrikePrice
/ us-gaap_DerivativeByNatureAxis
= us-gaap_PutOptionMember
/ us-gaap_DerivativeInstrumentRiskAxis
= wex_OptionsSettlingJulyTwoThousandThirteenToMarchTwoThousandFourteenMember
/ wex_FuelPriceDerivativesByTypeOfFuelAxis
= wex_DieselFuelMember		 [2]  
Put Option | Diesel | Options settling April 2015 – December 2015    
Derivatives, Fair Value [Line Items]    
Total fuel price derivative instruments, Strike Price of Underlying (per gallon) 3.785us-gaap_DerivativePriceRiskOptionStrikePrice
/ us-gaap_DerivativeByNatureAxis
= us-gaap_PutOptionMember
/ us-gaap_DerivativeInstrumentRiskAxis
= wex_OptionsSettlingAprilTwoThousandThirteenToDecemberTwoThousandThirteenMember
/ wex_FuelPriceDerivativesByTypeOfFuelAxis
= wex_DieselFuelMember		 [2]  
Put Option | Diesel | Options settling January 2015 – September 2015    
Derivatives, Fair Value [Line Items]    
Total fuel price derivative instruments, Strike Price of Underlying (per gallon) 3.795us-gaap_DerivativePriceRiskOptionStrikePrice
/ us-gaap_DerivativeByNatureAxis
= us-gaap_PutOptionMember
/ us-gaap_DerivativeInstrumentRiskAxis
= wex_OptionsSettlingJanuaryTwoThousandThirteenToSeptemberTwoThousandThirteenMember
/ wex_FuelPriceDerivativesByTypeOfFuelAxis
= wex_DieselFuelMember		 [2]  
Put Option | Diesel | Options settling October 2014 – June 2015    
Derivatives, Fair Value [Line Items]    
Total fuel price derivative instruments, Strike Price of Underlying (per gallon) 3.785us-gaap_DerivativePriceRiskOptionStrikePrice
/ us-gaap_DerivativeByNatureAxis
= us-gaap_PutOptionMember
/ us-gaap_DerivativeInstrumentRiskAxis
= wex_OptionsSettlingOctoberTwoThousandTwelveToJuneTwoThousandThirteenMember
/ wex_FuelPriceDerivativesByTypeOfFuelAxis
= wex_DieselFuelMember		 [2]  
Put Option | Diesel | Options settling July 2014 – March 2015    
Derivatives, Fair Value [Line Items]    
Total fuel price derivative instruments, Strike Price of Underlying (per gallon) 3.788us-gaap_DerivativePriceRiskOptionStrikePrice
/ us-gaap_DerivativeByNatureAxis
= us-gaap_PutOptionMember
/ us-gaap_DerivativeInstrumentRiskAxis
= wex_OptionsSettlingJulyTwoThousandTwelveToMarchTwoThousandThirteenMember
/ wex_FuelPriceDerivativesByTypeOfFuelAxis
= wex_DieselFuelMember		 [2]  
Put Option | Diesel | Options settling April 2014 – December 2014    
Derivatives, Fair Value [Line Items]    
Total fuel price derivative instruments, Strike Price of Underlying (per gallon) 3.800us-gaap_DerivativePriceRiskOptionStrikePrice
/ us-gaap_DerivativeByNatureAxis
= us-gaap_PutOptionMember
/ us-gaap_DerivativeInstrumentRiskAxis
= wex_OptionsSettlingAprilTwoThousandTwelveToDecemberTwoThousandTwelveMember
/ wex_FuelPriceDerivativesByTypeOfFuelAxis
= wex_DieselFuelMember		 [2]  
Put Option | Diesel | Options settling January 2014– September 2014    
Derivatives, Fair Value [Line Items]    
Total fuel price derivative instruments, Strike Price of Underlying (per gallon) 3.810us-gaap_DerivativePriceRiskOptionStrikePrice
/ us-gaap_DerivativeByNatureAxis
= us-gaap_PutOptionMember
/ us-gaap_DerivativeInstrumentRiskAxis
= wex_OptionsSettlingJanuaryTwoThousandTwelveToSeptemberTwoThousandTwelveMember
/ wex_FuelPriceDerivativesByTypeOfFuelAxis
= wex_DieselFuelMember		 [2]  
Put Option | Diesel | Options settling October 2013 – June 2014    
Derivatives, Fair Value [Line Items]    
Total fuel price derivative instruments, Strike Price of Underlying (per gallon) 3.713us-gaap_DerivativePriceRiskOptionStrikePrice
/ us-gaap_DerivativeByNatureAxis
= us-gaap_PutOptionMember
/ us-gaap_DerivativeInstrumentRiskAxis
= wex_OptionsSettlingOctoberTwoThousandElevenToJuneTwoThousandTwelveMember
/ wex_FuelPriceDerivativesByTypeOfFuelAxis
= wex_DieselFuelMember		 [2]  
Put Option | Diesel | Options settling July 2013 – March 2014    
Derivatives, Fair Value [Line Items]    
Total fuel price derivative instruments, Strike Price of Underlying (per gallon) 3.878us-gaap_DerivativePriceRiskOptionStrikePrice
/ us-gaap_DerivativeByNatureAxis
= us-gaap_PutOptionMember
/ us-gaap_DerivativeInstrumentRiskAxis
= wex_OptionsSettlingJulyTwoThousandElevenToMarchTwoThousandTwelveMember
/ wex_FuelPriceDerivativesByTypeOfFuelAxis
= wex_DieselFuelMember		 [2]  
Call Option | Unleaded Fuel | Options settling July 2015 – March 2016    
Derivatives, Fair Value [Line Items]    
Total fuel price derivative instruments, Strike Price of Underlying (per gallon) 2.543us-gaap_DerivativePriceRiskOptionStrikePrice
/ us-gaap_DerivativeByNatureAxis
= us-gaap_CallOptionMember
/ us-gaap_DerivativeInstrumentRiskAxis
= wex_OptionsSettlingJulyTwoThousandThirteenToMarchTwoThousandFourteenMember
/ wex_FuelPriceDerivativesByTypeOfFuelAxis
= wex_UnleadedFuelMember		 [2]  
Call Option | Unleaded Fuel | Options settling April 2015 – December 2015    
Derivatives, Fair Value [Line Items]    
Total fuel price derivative instruments, Strike Price of Underlying (per gallon) 2.680us-gaap_DerivativePriceRiskOptionStrikePrice
/ us-gaap_DerivativeByNatureAxis
= us-gaap_CallOptionMember
/ us-gaap_DerivativeInstrumentRiskAxis
= wex_OptionsSettlingAprilTwoThousandThirteenToDecemberTwoThousandThirteenMember
/ wex_FuelPriceDerivativesByTypeOfFuelAxis
= wex_UnleadedFuelMember		 [2]  
Call Option | Unleaded Fuel | Options settling January 2015 – September 2015    
Derivatives, Fair Value [Line Items]    
Total fuel price derivative instruments, Strike Price of Underlying (per gallon) 2.685us-gaap_DerivativePriceRiskOptionStrikePrice
/ us-gaap_DerivativeByNatureAxis
= us-gaap_CallOptionMember
/ us-gaap_DerivativeInstrumentRiskAxis
= wex_OptionsSettlingJanuaryTwoThousandThirteenToSeptemberTwoThousandThirteenMember
/ wex_FuelPriceDerivativesByTypeOfFuelAxis
= wex_UnleadedFuelMember		 [2]  
Call Option | Unleaded Fuel | Options settling October 2014 – June 2015    
Derivatives, Fair Value [Line Items]    
Total fuel price derivative instruments, Strike Price of Underlying (per gallon) 2.628us-gaap_DerivativePriceRiskOptionStrikePrice
/ us-gaap_DerivativeByNatureAxis
= us-gaap_CallOptionMember
/ us-gaap_DerivativeInstrumentRiskAxis
= wex_OptionsSettlingOctoberTwoThousandTwelveToJuneTwoThousandThirteenMember
/ wex_FuelPriceDerivativesByTypeOfFuelAxis
= wex_UnleadedFuelMember		 [2]  
Call Option | Unleaded Fuel | Options settling July 2014 – March 2015    
Derivatives, Fair Value [Line Items]    
Total fuel price derivative instruments, Strike Price of Underlying (per gallon) 2.570us-gaap_DerivativePriceRiskOptionStrikePrice
/ us-gaap_DerivativeByNatureAxis
= us-gaap_CallOptionMember
/ us-gaap_DerivativeInstrumentRiskAxis
= wex_OptionsSettlingJulyTwoThousandTwelveToMarchTwoThousandThirteenMember
/ wex_FuelPriceDerivativesByTypeOfFuelAxis
= wex_UnleadedFuelMember		 [2]  
Call Option | Unleaded Fuel | Options settling April 2014 – December 2014    
Derivatives, Fair Value [Line Items]    
Total fuel price derivative instruments, Strike Price of Underlying (per gallon) 2.675us-gaap_DerivativePriceRiskOptionStrikePrice
/ us-gaap_DerivativeByNatureAxis
= us-gaap_CallOptionMember
/ us-gaap_DerivativeInstrumentRiskAxis
= wex_OptionsSettlingAprilTwoThousandTwelveToDecemberTwoThousandTwelveMember
/ wex_FuelPriceDerivativesByTypeOfFuelAxis
= wex_UnleadedFuelMember		 [2]  
Call Option | Unleaded Fuel | Options settling January 2014– September 2014    
Derivatives, Fair Value [Line Items]    
Total fuel price derivative instruments, Strike Price of Underlying (per gallon) 2.760us-gaap_DerivativePriceRiskOptionStrikePrice
/ us-gaap_DerivativeByNatureAxis
= us-gaap_CallOptionMember
/ us-gaap_DerivativeInstrumentRiskAxis
= wex_OptionsSettlingJanuaryTwoThousandTwelveToSeptemberTwoThousandTwelveMember
/ wex_FuelPriceDerivativesByTypeOfFuelAxis
= wex_UnleadedFuelMember		 [2]  
Call Option | Unleaded Fuel | Options settling October 2013 – June 2014    
Derivatives, Fair Value [Line Items]    
Total fuel price derivative instruments, Strike Price of Underlying (per gallon) 2.545us-gaap_DerivativePriceRiskOptionStrikePrice
/ us-gaap_DerivativeByNatureAxis
= us-gaap_CallOptionMember
/ us-gaap_DerivativeInstrumentRiskAxis
= wex_OptionsSettlingOctoberTwoThousandElevenToJuneTwoThousandTwelveMember
/ wex_FuelPriceDerivativesByTypeOfFuelAxis
= wex_UnleadedFuelMember		 [2]  
Call Option | Unleaded Fuel | Options settling July 2013 – March 2014    
Derivatives, Fair Value [Line Items]    
Total fuel price derivative instruments, Strike Price of Underlying (per gallon) 2.693us-gaap_DerivativePriceRiskOptionStrikePrice
/ us-gaap_DerivativeByNatureAxis
= us-gaap_CallOptionMember
/ us-gaap_DerivativeInstrumentRiskAxis
= wex_OptionsSettlingJulyTwoThousandElevenToMarchTwoThousandTwelveMember
/ wex_FuelPriceDerivativesByTypeOfFuelAxis
= wex_UnleadedFuelMember		 [2]  
Call Option | Diesel | Options settling July 2015 – March 2016    
Derivatives, Fair Value [Line Items]    
Total fuel price derivative instruments, Strike Price of Underlying (per gallon) 3.784us-gaap_DerivativePriceRiskOptionStrikePrice
/ us-gaap_DerivativeByNatureAxis
= us-gaap_CallOptionMember
/ us-gaap_DerivativeInstrumentRiskAxis
= wex_OptionsSettlingJulyTwoThousandThirteenToMarchTwoThousandFourteenMember
/ wex_FuelPriceDerivativesByTypeOfFuelAxis
= wex_DieselFuelMember		 [2]  
Call Option | Diesel | Options settling April 2015 – December 2015    
Derivatives, Fair Value [Line Items]    
Total fuel price derivative instruments, Strike Price of Underlying (per gallon) 3.845us-gaap_DerivativePriceRiskOptionStrikePrice
/ us-gaap_DerivativeByNatureAxis
= us-gaap_CallOptionMember
/ us-gaap_DerivativeInstrumentRiskAxis
= wex_OptionsSettlingAprilTwoThousandThirteenToDecemberTwoThousandThirteenMember
/ wex_FuelPriceDerivativesByTypeOfFuelAxis
= wex_DieselFuelMember		 [2]  
Call Option | Diesel | Options settling January 2015 – September 2015    
Derivatives, Fair Value [Line Items]    
Total fuel price derivative instruments, Strike Price of Underlying (per gallon) 3.855us-gaap_DerivativePriceRiskOptionStrikePrice
/ us-gaap_DerivativeByNatureAxis
= us-gaap_CallOptionMember
/ us-gaap_DerivativeInstrumentRiskAxis
= wex_OptionsSettlingJanuaryTwoThousandThirteenToSeptemberTwoThousandThirteenMember
/ wex_FuelPriceDerivativesByTypeOfFuelAxis
= wex_DieselFuelMember		 [2]  
Call Option | Diesel | Options settling October 2014 – June 2015    
Derivatives, Fair Value [Line Items]    
Total fuel price derivative instruments, Strike Price of Underlying (per gallon) 3.845us-gaap_DerivativePriceRiskOptionStrikePrice
/ us-gaap_DerivativeByNatureAxis
= us-gaap_CallOptionMember
/ us-gaap_DerivativeInstrumentRiskAxis
= wex_OptionsSettlingOctoberTwoThousandTwelveToJuneTwoThousandThirteenMember
/ wex_FuelPriceDerivativesByTypeOfFuelAxis
= wex_DieselFuelMember		 [2]  
Call Option | Diesel | Options settling July 2014 – March 2015    
Derivatives, Fair Value [Line Items]    
Total fuel price derivative instruments, Strike Price of Underlying (per gallon) 3.848us-gaap_DerivativePriceRiskOptionStrikePrice
/ us-gaap_DerivativeByNatureAxis
= us-gaap_CallOptionMember
/ us-gaap_DerivativeInstrumentRiskAxis
= wex_OptionsSettlingJulyTwoThousandTwelveToMarchTwoThousandThirteenMember
/ wex_FuelPriceDerivativesByTypeOfFuelAxis
= wex_DieselFuelMember		 [2]  
Call Option | Diesel | Options settling April 2014 – December 2014    
Derivatives, Fair Value [Line Items]    
Total fuel price derivative instruments, Strike Price of Underlying (per gallon) 3.860us-gaap_DerivativePriceRiskOptionStrikePrice
/ us-gaap_DerivativeByNatureAxis
= us-gaap_CallOptionMember
/ us-gaap_DerivativeInstrumentRiskAxis
= wex_OptionsSettlingAprilTwoThousandTwelveToDecemberTwoThousandTwelveMember
/ wex_FuelPriceDerivativesByTypeOfFuelAxis
= wex_DieselFuelMember		 [2]  
Call Option | Diesel | Options settling January 2014– September 2014    
Derivatives, Fair Value [Line Items]    
Total fuel price derivative instruments, Strike Price of Underlying (per gallon) 3.870us-gaap_DerivativePriceRiskOptionStrikePrice
/ us-gaap_DerivativeByNatureAxis
= us-gaap_CallOptionMember
/ us-gaap_DerivativeInstrumentRiskAxis
= wex_OptionsSettlingJanuaryTwoThousandTwelveToSeptemberTwoThousandTwelveMember
/ wex_FuelPriceDerivativesByTypeOfFuelAxis
= wex_DieselFuelMember		 [2]  
Call Option | Diesel | Options settling October 2013 – June 2014    
Derivatives, Fair Value [Line Items]    
Total fuel price derivative instruments, Strike Price of Underlying (per gallon) 3.773us-gaap_DerivativePriceRiskOptionStrikePrice
/ us-gaap_DerivativeByNatureAxis
= us-gaap_CallOptionMember
/ us-gaap_DerivativeInstrumentRiskAxis
= wex_OptionsSettlingOctoberTwoThousandElevenToJuneTwoThousandTwelveMember
/ wex_FuelPriceDerivativesByTypeOfFuelAxis
= wex_DieselFuelMember		 [2]  
Call Option | Diesel | Options settling July 2013 – March 2014    
Derivatives, Fair Value [Line Items]    
Total fuel price derivative instruments, Strike Price of Underlying (per gallon) 3.938us-gaap_DerivativePriceRiskOptionStrikePrice
/ us-gaap_DerivativeByNatureAxis
= us-gaap_CallOptionMember
/ us-gaap_DerivativeInstrumentRiskAxis
= wex_OptionsSettlingJulyTwoThousandElevenToMarchTwoThousandTwelveMember
/ wex_FuelPriceDerivativesByTypeOfFuelAxis
= wex_DieselFuelMember		 [2]  
[1] The Options settle on a monthly basis.
[2] The settlement of the Options 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.