v2.4.1.9
Financing Debt - Additional Information - Other (Details) (USD $)
In Thousands, unless otherwise specified
Dec. 31, 2014
Dec. 31, 2013
Debt Instrument [Line Items]    
Outstanding borrowings against federal funds lines-of-credit $ 901,564us-gaap_LineOfCredit $ 285,000us-gaap_LineOfCredit
Amount available for borrowings 269,182us-gaap_LineOfCreditFacilityCurrentBorrowingCapacity  
Pledged receivables held as collateral 488,976us-gaap_PledgedAssetsSeparatelyReportedFinanceReceivablesPledgedAsCollateralAtFairValue  
Letter of Credit | Revolving Credit Facility | 2011 Credit Agreement    
Debt Instrument [Line Items]    
Outstanding borrowings against federal funds lines-of-credit 5,150us-gaap_LineOfCredit
/ us-gaap_CreditFacilityAxis
= us-gaap_RevolvingCreditFacilityMember
/ us-gaap_LineOfCreditFacilityAxis
= wex_TwoThousandAndElevenCreditAgreementMember
/ us-gaap_ShortTermDebtTypeAxis
= us-gaap_LetterOfCreditMember
 
2014 Credit Agreement    
Debt Instrument [Line Items]    
Amount available for borrowings $ 279,536us-gaap_LineOfCreditFacilityCurrentBorrowingCapacity
/ us-gaap_DebtInstrumentAxis
= wex_TwoThousandAndFourteenCreditAgreementMember