v2.4.1.9
Business Acquisitions and Other Intangible Assets Acquisitions - Additional Information - Acquisition of FleetOne (Details) (USD $)
In Thousands, unless otherwise specified
 3 Months Ended 12 Months Ended 0 Months Ended 3 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
Dec. 31, 2013
Dec. 31, 2012
Oct. 04, 2012
Dec. 31, 2012
Business Acquisition [Line Items]                          
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    
Net earnings attributable to WEX Inc. 47,893us-gaap_NetIncomeLoss 74,443us-gaap_NetIncomeLoss 43,333us-gaap_NetIncomeLoss 36,542us-gaap_NetIncomeLoss 34,468us-gaap_NetIncomeLoss 43,838us-gaap_NetIncomeLoss 42,213us-gaap_NetIncomeLoss 28,689us-gaap_NetIncomeLoss 202,211us-gaap_NetIncomeLoss 149,208us-gaap_NetIncomeLoss 96,922us-gaap_NetIncomeLoss    
FleetOne                          
Business Acquisition [Line Items]                          
Payments to acquire business                       376,258us-gaap_PaymentsToAcquireBusinessesGross
/ us-gaap_BusinessAcquisitionAxis
= wex_FleetOneMember		  
Net revenues                         14,200us-gaap_SalesRevenueNet
/ us-gaap_BusinessAcquisitionAxis
= wex_FleetOneMember
Net earnings attributable to WEX Inc.                         $ 1,400us-gaap_NetIncomeLoss
/ us-gaap_BusinessAcquisitionAxis
= wex_FleetOneMember