v2.4.1.9
Fair Value - Reconciliation of Beginning and Ending Balances for Assets (Liabilities) Measured at Fair Value on Recurring Basis Using Significant Unobservable Inputs (Level Three) (Details) (USD $)
In Thousands, unless otherwise specified
 12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Fuel price derivatives - diesel    
Fuel Price Derivatives – Diesel    
Beginning balance $ (2,142)us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs
/ us-gaap_FinancialInstrumentAxis
= wex_FuelPriceDerivativesDieselMember		 $ (107)us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs
/ us-gaap_FinancialInstrumentAxis
= wex_FuelPriceDerivativesDieselMember
Total gains or (losses) - realized/unrealized Included in earnings 13,990us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1
/ us-gaap_FinancialInstrumentAxis
= wex_FuelPriceDerivativesDieselMember		 [1] (2,035)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1
/ us-gaap_FinancialInstrumentAxis
= wex_FuelPriceDerivativesDieselMember		 [2]
Ending balance 11,848us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs
/ us-gaap_FinancialInstrumentAxis
= wex_FuelPriceDerivativesDieselMember		 (2,142)us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs
/ us-gaap_FinancialInstrumentAxis
= wex_FuelPriceDerivativesDieselMember
Contingent Consideration    
Ending balance (11,849)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue
/ us-gaap_FinancialInstrumentAxis
= wex_FuelPriceDerivativesDieselMember		  
Contingent Consideration    
Contingent Consideration    
Beginning balance   (313)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue
/ us-gaap_FinancialInstrumentAxis
= wex_ContingentConsiderationMember
Included in earnings   (198)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityGainLossIncludedInEarnings
/ us-gaap_FinancialInstrumentAxis
= wex_ContingentConsiderationMember		 [2]
Transfers in/(out) of Level 3   511us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityTransfersNet
/ us-gaap_FinancialInstrumentAxis
= wex_ContingentConsiderationMember
Ending balance   $ 0us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue
/ us-gaap_FinancialInstrumentAxis
= wex_ContingentConsiderationMember
[1] Gains and losses (realized and unrealized) included in earnings for the year ended December 31, 2014, are reported in net realized and unrealized gains and (losses) on fuel price derivatives on the consolidated statements of income.
[2] Gains and losses (realized and unrealized) included in earnings for the year ended December 31, 2013, are reported in net realized and unrealized gains and (losses) on fuel price derivatives on the consolidated statements of income. Gains and losses on the change of estimate on the contingent consideration are included in other expenses and loss of foreign currency transactions on the consolidated statements of income.