v2.4.1.9
Segment Information - Additional Information (Detail) (USD $)
In Thousands, unless otherwise specified
3 Months Ended 12 Months Ended 6 Months Ended
Dec. 31, 2014
Sep. 30, 2014
Jun. 30, 2014
Mar. 31, 2014
Dec. 31, 2013
Sep. 30, 2013
Jun. 30, 2013
Mar. 31, 2013
Dec. 31, 2014
Segment
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2014
Concentration Risk [Line Items]                        
Number of reportable segments                 2us-gaap_NumberOfReportableSegments      
Net revenues $ 211,864us-gaap_SalesRevenueNet $ 222,134us-gaap_SalesRevenueNet $ 201,581us-gaap_SalesRevenueNet $ 182,068us-gaap_SalesRevenueNet $ 182,283us-gaap_SalesRevenueNet $ 191,525us-gaap_SalesRevenueNet $ 178,285us-gaap_SalesRevenueNet $ 165,370us-gaap_SalesRevenueNet $ 817,647us-gaap_SalesRevenueNet $ 717,463us-gaap_SalesRevenueNet $ 623,151us-gaap_SalesRevenueNet  
Accounts Receivable | Customer Concentration Risk                        
Concentration Risk [Line Items]                        
Number of customers 0wex_ConcentrationRiskNumberofCustomers
/ us-gaap_ConcentrationRiskByBenchmarkAxis
= us-gaap_AccountsReceivableMember
/ us-gaap_ConcentrationRiskByTypeAxis
= us-gaap_CustomerConcentrationRiskMember
              0wex_ConcentrationRiskNumberofCustomers
/ us-gaap_ConcentrationRiskByBenchmarkAxis
= us-gaap_AccountsReceivableMember
/ us-gaap_ConcentrationRiskByTypeAxis
= us-gaap_CustomerConcentrationRiskMember
    0wex_ConcentrationRiskNumberofCustomers
/ us-gaap_ConcentrationRiskByBenchmarkAxis
= us-gaap_AccountsReceivableMember
/ us-gaap_ConcentrationRiskByTypeAxis
= us-gaap_CustomerConcentrationRiskMember
Concentration Risk, Percentage (less than 7 percent for total revenues)                 10.00%us-gaap_ConcentrationRiskPercentage1
/ us-gaap_ConcentrationRiskByBenchmarkAxis
= us-gaap_AccountsReceivableMember
/ us-gaap_ConcentrationRiskByTypeAxis
= us-gaap_CustomerConcentrationRiskMember
     
Sales Revenue, Net | Customer Concentration Risk                        
Concentration Risk [Line Items]                        
Concentration Risk, Percentage (less than 7 percent for total revenues)                 7.30%us-gaap_ConcentrationRiskPercentage1
/ us-gaap_ConcentrationRiskByBenchmarkAxis
= us-gaap_SalesRevenueNetMember
/ us-gaap_ConcentrationRiskByTypeAxis
= us-gaap_CustomerConcentrationRiskMember
     
International                        
Concentration Risk [Line Items]                        
Net revenues                 50,923us-gaap_SalesRevenueNet
/ us-gaap_StatementGeographicalAxis
= wex_InternationalMember
28,536us-gaap_SalesRevenueNet
/ us-gaap_StatementGeographicalAxis
= wex_InternationalMember
12,815us-gaap_SalesRevenueNet
/ us-gaap_StatementGeographicalAxis
= wex_InternationalMember
 
Maximum | International | Sales Revenue, Net | Geographic Concentration Risk                        
Concentration Risk [Line Items]                        
Concentration Risk, Percentage (less than 7 percent for total revenues)                 3.00%us-gaap_ConcentrationRiskPercentage1
/ us-gaap_ConcentrationRiskByBenchmarkAxis
= us-gaap_SalesRevenueNetMember
/ us-gaap_ConcentrationRiskByTypeAxis
= us-gaap_GeographicConcentrationRiskMember
/ us-gaap_RangeAxis
= us-gaap_MaximumMember
/ us-gaap_StatementGeographicalAxis
= wex_InternationalMember
     
Evolution1                        
Concentration Risk [Line Items]                        
Net revenues                       $ 35,976us-gaap_SalesRevenueNet
/ us-gaap_BusinessAcquisitionAxis
= wex_EvolutionOneMember