v2.4.1.9

Deposits, Borrowed Federal Funds and Other Debt - Additional Information (Details) (USD $)	12 Months Ended	9 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Dec. 31, 2013	Dec. 31, 2012
Deposit Liabilities And Borrowed Federal Funds [Line Items]
Certificates of deposit, denominations ($250 or less)	250,000wex_CertificatesOfDepositsDenominationsInDollarAmount
Federal funds lines-of-credit	125,000,000us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity		125,000,000us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
Weighted average interest rate on interest-bearing money market deposits	0.25%us-gaap_WeightedAverageRateDomesticDepositMoneyMarket		0.25%us-gaap_WeightedAverageRateDomesticDepositMoneyMarket
Non-interest bearing deposits outstanding	314,576,000wex_NonInterestbearingDomesticDepositNegotiableOrderOfWithdrawalNow		276,422,000wex_NonInterestbearingDomesticDepositNegotiableOrderOfWithdrawalNow
Debt outstanding	0us-gaap_LineOfCreditFacilityFairValueOfAmountOutstanding		0us-gaap_LineOfCreditFacilityFairValueOfAmountOutstanding
Interest-bearing Deposits
Deposit Liabilities And Borrowed Federal Funds [Line Items]
Interest-bearing money market deposits, denominations	250,000wex_InterestBearingDepositsDenominationsInDollarAmount / us-gaap_InvestmentTypeAxis = us-gaap_InterestBearingDepositsMember
Weighted average interest rate on interest-bearing money market deposits	0.25%us-gaap_WeightedAverageRateDomesticDepositMoneyMarket / us-gaap_InvestmentTypeAxis = us-gaap_InterestBearingDepositsMember
Minimum
Deposit Liabilities And Borrowed Federal Funds [Line Items]
Certificates of deposit, maturities range	2 months
Certificates of deposit, fixed interest rates range	0.35%wex_CertificateOfDepositsFixedInterestRatesRange / us-gaap_RangeAxis = us-gaap_MinimumMember
Maximum
Deposit Liabilities And Borrowed Federal Funds [Line Items]
Certificates of deposit, maturities range	2 years
Certificates of deposit, fixed interest rates range	1.05%wex_CertificateOfDepositsFixedInterestRatesRange / us-gaap_RangeAxis = us-gaap_MaximumMember
Unik Financial Services
Deposit Liabilities And Borrowed Federal Funds [Line Items]
Debt outstanding	7,975,000us-gaap_LineOfCreditFacilityFairValueOfAmountOutstanding / us-gaap_BusinessAcquisitionAxis = wex_UnikSAMember		7,278,000us-gaap_LineOfCreditFacilityFairValueOfAmountOutstanding / 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
Participation Agreement
Deposit Liabilities And Borrowed Federal Funds [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
Debt instrument, aggregate principal amount		45,000,000us-gaap_DebtInstrumentFaceAmount / us-gaap_DebtInstrumentAxis = us-gaap_LoanParticipationsAndAssignmentsMember
Participation Agreement | Minimum
Deposit Liabilities And Borrowed Federal Funds [Line Items]
Long-term debt, range of daily balance		0wex_LongtermDebtRangeofDailyBalance / us-gaap_DebtInstrumentAxis = us-gaap_LoanParticipationsAndAssignmentsMember / us-gaap_RangeAxis = us-gaap_MinimumMember
Participation Agreement | Maximum
Deposit Liabilities And Borrowed Federal Funds [Line Items]
Long-term debt, range of daily balance		45,000,000wex_LongtermDebtRangeofDailyBalance / us-gaap_DebtInstrumentAxis = us-gaap_LoanParticipationsAndAssignmentsMember / us-gaap_RangeAxis = us-gaap_MaximumMember
Participation Agreement | London Interbank Offered Rate (LIBOR)
Deposit Liabilities And Borrowed Federal Funds [Line Items]
Variable interest rate margin		2.25%us-gaap_DebtInstrumentBasisSpreadOnVariableRate1 / us-gaap_DebtInstrumentAxis = us-gaap_LoanParticipationsAndAssignmentsMember / us-gaap_VariableRateAxis = us-gaap_LondonInterbankOfferedRateLIBORMember

X

- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Face (par) amount of debt instrument at time of issuance.

+ 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 FASB

-Name Accounting Standards Codification

-Topic 835

-SubTopic 30

-Section 55

-Paragraph 8

-URI http://asc.fasb.org/extlink&oid=34725769&loc=d3e28878-108400

+ Details

Name:	us-gaap_DebtInstrumentFaceAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

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

Fair value of the amount outstanding under the credit facility.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 825

-SubTopic 10

-Section 50

-Paragraph 10

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=35750535&loc=d3e13433-108611



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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 825

-SubTopic 10

-Section 50

-Paragraph 12

-URI http://asc.fasb.org/extlink&oid=35750535&loc=d3e13476-108611

+ Details

Name:	us-gaap_LineOfCreditFacilityFairValueOfAmountOutstanding
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

X

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

Reference 1: 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),22(b))

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



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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 19, 22

-Article 5

+ Details

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

X

- Definition

The weighted average interest rate for domestic money market demand account deposit liabilities.

+ References

No definition available.

+ Details

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

X

- Definition

Certificate of deposits fixed interest rates range

+ References

No definition available.

+ Details

Name:	wex_CertificateOfDepositsFixedInterestRatesRange
Namespace Prefix:	wex_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Certificate of deposits maturities range

+ References

No definition available.

+ Details

Name:	wex_CertificateOfDepositsMaturitiesRange
Namespace Prefix:	wex_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Certificates of deposits denominations in dollar amount

+ References

No definition available.

+ Details

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

X

- Details

Name:	wex_DepositLiabilitiesAndBorrowedFederalFundsLineItems
Namespace Prefix:	wex_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Interest bearing deposits denominations in dollar amount

+ References

No definition available.

+ Details

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

X

- Definition

Long-term Debt, Range of Daily Balance

+ References

No definition available.

+ Details

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

X

- Definition

Non Interest-bearing Domestic Deposit, Negotiable Order of Withdrawal (NOW)

+ References

No definition available.

+ Details

Name:	wex_NonInterestbearingDomesticDepositNegotiableOrderOfWithdrawalNow
Namespace Prefix:	wex_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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:

X

- Details

Name:	us-gaap_InvestmentTypeAxis=us-gaap_InterestBearingDepositsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

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Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: