v2.4.1.9

Income Taxes - Additional Information (Details) (USD $) In Thousands, unless otherwise specified	9 Months Ended	12 Months Ended			3 Months Ended	1 Months Ended
	Sep. 30, 2014	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Sep. 30, 2014	Jun. 30, 2012
Income Taxes [Line Items]
Undistributed earnings of certain foreign subsidiaries		$ 7,733us-gaap_DeferredTaxLiabilitiesUndistributedForeignEarnings	$ 4,665us-gaap_DeferredTaxLiabilitiesUndistributedForeignEarnings
Unrecognized tax benefits, net		6,844wex_UnrecognizedTaxBenefitsNet
Unrecognized tax benefits that, if recognized, would impact effective tax rate		6,844us-gaap_UnrecognizedTaxBenefitsThatWouldImpactEffectiveTaxRate
Accrued penalties and interest related to uncertain tax positions		1,988us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued	1,625us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued	1,313us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued
Income tax expense		101,621us-gaap_IncomeTaxExpenseBenefit	90,102us-gaap_IncomeTaxExpenseBenefit	109,474us-gaap_IncomeTaxExpenseBenefit
Write-off of refund claim payable to former shareholder of RD Card Holding		0wex_DecreaseInTaxRefundDueToFormerShareholders	0wex_DecreaseInTaxRefundDueToFormerShareholders	9,750wex_DecreaseInTaxRefundDueToFormerShareholders
Goodwill impairment		0us-gaap_GoodwillImpairmentLoss	0us-gaap_GoodwillImpairmentLoss	17,508us-gaap_GoodwillImpairmentLoss
Increase in income tax due to retroactive adjustment				2,400wex_IncreaseInIncomeTaxDueToImpactOfRetroactiveAdjustment
Reduction in tax expenses due to research and development credits	2,400us-gaap_TaxAdjustmentsSettlementsAndUnusualProvisions
Tax Years 2010 through 2013 [Member]
Income Taxes [Line Items]
Reduction in tax expenses due to research and development credits					11,300us-gaap_TaxAdjustmentsSettlementsAndUnusualProvisions / us-gaap_TaxPeriodAxis = wex_TaxYears2010through2013Member
State and Local Jurisdiction
Income Taxes [Line Items]
Operating loss carry forwards		645,132us-gaap_OperatingLossCarryforwards / us-gaap_IncomeTaxAuthorityAxis = us-gaap_StateAndLocalJurisdictionMember	561,469us-gaap_OperatingLossCarryforwards / us-gaap_IncomeTaxAuthorityAxis = us-gaap_StateAndLocalJurisdictionMember
Domestic Tax Authority
Income Taxes [Line Items]
Operating loss carry forwards		53,099us-gaap_OperatingLossCarryforwards / us-gaap_IncomeTaxAuthorityAxis = us-gaap_DomesticCountryMember
Domestic Tax Authority | Evolution1
Income Taxes [Line Items]
Operating loss carryforwards, utilized during period		7,363wex_OperatingLossCarryforwardsUtilizedDuringPeriod / us-gaap_BusinessAcquisitionAxis = wex_EvolutionOneMember / us-gaap_IncomeTaxAuthorityAxis = us-gaap_DomesticCountryMember
Foreign Tax Authority
Income Taxes [Line Items]
Operating loss carry forwards		53,609us-gaap_OperatingLossCarryforwards / us-gaap_IncomeTaxAuthorityAxis = us-gaap_ForeignCountryMember	31,489us-gaap_OperatingLossCarryforwards / us-gaap_IncomeTaxAuthorityAxis = us-gaap_ForeignCountryMember
Australia
Income Taxes [Line Items]
Income tax expense						31,432us-gaap_IncomeTaxExpenseBenefit / us-gaap_IncomeTaxAuthorityAxis = country_AU
Write-off of refund claim payable to former shareholder of RD Card Holding						$ 9,750wex_DecreaseInTaxRefundDueToFormerShareholders / us-gaap_IncomeTaxAuthorityAxis = country_AU

X

- Definition

Amount of deferred tax liability attributable to taxable temporary differences from undistributed earnings of subsidiaries and other recognized entities not within the country of domicile of the entity.

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Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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Amount of increase (decrease) to previously recorded tax expense. Includes, but is not limited to, significant settlements of income tax disputes, and unusual tax positions or infrequent actions taken by the entity, including tax assessment reversal, and IRS tax settlement.

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Amount accrued for interest on an underpayment of income taxes and penalties related to a tax position claimed or expected to be claimed in the tax return.

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