v2.4.1.9

Deposits, Borrowed Federal Funds and Other Debt - Average Interest Rate (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Debt Instrument [Line Items]
Deposits	0.53%us-gaap_WeightedAverageRateDomesticDeposit	0.51%us-gaap_WeightedAverageRateDomesticDeposit	0.65%us-gaap_WeightedAverageRateDomesticDeposit
Borrowed federal funds	0.38%us-gaap_FederalHomeLoanBankAdvancesBranchOfFHLBBankWeightedAverageInterestRate	0.41%us-gaap_FederalHomeLoanBankAdvancesBranchOfFHLBBankWeightedAverageInterestRate	0.42%us-gaap_FederalHomeLoanBankAdvancesBranchOfFHLBBankWeightedAverageInterestRate
Negotiable order of withdrawal deposits	0.00%wex_WeightedAverageRateDomesticDepositNegotiableOrderOfWithdrawalNow	0.00%wex_WeightedAverageRateDomesticDepositNegotiableOrderOfWithdrawalNow	0.00%wex_WeightedAverageRateDomesticDepositNegotiableOrderOfWithdrawalNow
Interest-bearing money market deposits	0.23%us-gaap_PercentageOfInterestBearingDomesticDepositsToDepositsMoneyMarket	0.31%us-gaap_PercentageOfInterestBearingDomesticDepositsToDepositsMoneyMarket	0.49%us-gaap_PercentageOfInterestBearingDomesticDepositsToDepositsMoneyMarket
Average deposits and borrowed federal funds balance	$ 1,220,979wex_AverageDebtBalance	$ 1,012,806wex_AverageDebtBalance	$ 888,135wex_AverageDebtBalance
Average other debt (UNIK and participation agreement)	$ 37,876us-gaap_LineOfCreditFacilityAverageOutstandingAmount	$ 8,767us-gaap_LineOfCreditFacilityAverageOutstandingAmount	$ 9,823us-gaap_LineOfCreditFacilityAverageOutstandingAmount
Participation Agreement
Debt Instrument [Line Items]
Weighted average interest rate	2.46%us-gaap_DebtWeightedAverageInterestRate / us-gaap_DebtInstrumentAxis = us-gaap_LoanParticipationsAndAssignmentsMember	0.00%us-gaap_DebtWeightedAverageInterestRate / us-gaap_DebtInstrumentAxis = us-gaap_LoanParticipationsAndAssignmentsMember	0.00%us-gaap_DebtWeightedAverageInterestRate / us-gaap_DebtInstrumentAxis = us-gaap_LoanParticipationsAndAssignmentsMember
Unik Financial Services
Debt Instrument [Line Items]
UNIK debt	17.15%us-gaap_DebtInstrumentInterestRateDuringPeriod / us-gaap_BusinessAcquisitionAxis = wex_UnikSAMember	17.04%us-gaap_DebtInstrumentInterestRateDuringPeriod / us-gaap_BusinessAcquisitionAxis = wex_UnikSAMember	22.45%us-gaap_DebtInstrumentInterestRateDuringPeriod / us-gaap_BusinessAcquisitionAxis = wex_UnikSAMember
Weighted average interest rate	13.90%us-gaap_DebtWeightedAverageInterestRate / us-gaap_BusinessAcquisitionAxis = wex_UnikSAMember	15.80%us-gaap_DebtWeightedAverageInterestRate / us-gaap_BusinessAcquisitionAxis = wex_UnikSAMember

X

- Definition

The average effective interest rate during the reporting period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

-SubTopic 30

-Section 45

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28551-108399



Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 22

-Article 5



Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.22(a)(1))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

X

- Details

Name:	us-gaap_DebtInstrumentLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Weighted average interest rate of debt outstanding.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtWeightedAverageInterestRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

X

- Definition

Describes the weighted average interest rate applicable to the specific advances from the Federal Home Loan Bank, by branch, as of the Balance Sheet date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 470

-Section 45

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6479118&loc=d3e64650-112822



Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 470

-Section 50

-Paragraph 3

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=6479336&loc=d3e64711-112823



Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.19(b))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

X

- Definition

Average amount borrowed under the credit facility during the period.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

X

- Definition

Percentage of interest-bearing domestic money market demand account deposit liabilities to total deposit liabilities.

+ References

No definition available.

+ Details

Name:	us-gaap_PercentageOfInterestBearingDomesticDepositsToDepositsMoneyMarket
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

X

- Definition

The weighted average interest rate for all domestic deposit liabilities.

+ References

No definition available.

+ Details

Name:	us-gaap_WeightedAverageRateDomesticDeposit
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

X

- Definition

Average debt balance

+ References

No definition available.

+ Details

Name:	wex_AverageDebtBalance
Namespace Prefix:	wex_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

X

- Definition

Weighted Average Rate Domestic Deposit Negotiable Order Of Withdrawal Now

+ References

No definition available.

+ Details

Name:	wex_WeightedAverageRateDomesticDepositNegotiableOrderOfWithdrawalNow
Namespace Prefix:	wex_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

X

- Details

Name:	us-gaap_BusinessAcquisitionAxis=wex_UnikSAMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_DebtInstrumentAxis=us-gaap_LoanParticipationsAndAssignmentsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: