v2.4.1.9

Employee Benefit Plans - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended			0 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Jan. 02, 2015
Defined Benefit Plan Disclosure [Line Items]
Eligible age to participate	18 years
Hours worked to be eligible to participate (at least)	1000 hours
Eligible year of service for Company matching contributions	1 year
Company matching percentage of each employee's contributions to maximum employee eligible compensation	100.00%us-gaap_DefinedContributionPlanEmployerMatchingContributionPercent
Maximum percentage of employee eligible compensation to the plan	6.00%us-gaap_DefinedContributionPlanMaximumAnnualContributionsPerEmployeePercent
Contributions by company	$ 3,502us-gaap_DefinedContributionPlanCostRecognized	$ 2,991us-gaap_DefinedContributionPlanCostRecognized	$ 2,295us-gaap_DefinedContributionPlanCostRecognized
Obligation related to defined contribution plan	5,927us-gaap_DefinedBenefitPlanBenefitObligation	4,339us-gaap_DefinedBenefitPlanBenefitObligation
Aggregate market value of the securities	5,927us-gaap_DefinedBenefitPlanFairValueOfPlanAssets	4,339us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
Evolution1 | Subsequent Event
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets received from acquisition				21,739wex_DefinedBenefitPlanFairValueofPlanAssetsReceivedfromAcquisition / us-gaap_BusinessAcquisitionAxis = wex_EvolutionOneMember / us-gaap_SubsequentEventTypeAxis = us-gaap_SubsequentEventMember
ESSO Portfolio | Foreign Postretirement Benefit Plan
Defined Benefit Plan Disclosure [Line Items]
Obligation related to defined contribution plan	$ 4,900us-gaap_DefinedBenefitPlanBenefitObligation / us-gaap_BusinessAcquisitionAxis = wex_ESSOPortfolioMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_ForeignPostretirementBenefitPlansDefinedBenefitMember

X

- Definition

1) For defined benefit pension plans, the benefit obligation is the projected benefit obligation, which is the actuarial present value as of a date of all benefits attributed by the pension benefit formula to employee service rendered prior to that date. 2) For other postretirement defined benefit plans, the benefit obligation is the accumulated postretirement benefit obligation, which is the actuarial present value of benefits attributed to employee service rendered to a particular date.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=35743120&loc=d3e1928-114920



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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Projected Benefit Obligation

-URI http://asc.fasb.org/extlink&oid=6522206



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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Accumulated Postretirement Benefit Obligation

-URI http://asc.fasb.org/extlink&oid=6503904

+ Details

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

X

- Details

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

X

- Definition

Assets, usually stocks, bonds, and other investments, that have been segregated and restricted (usually in a trust) to provide benefits, at their fair value as of the measurement date. Plan assets include amounts contributed by the employer (and by employees for a contributory plan) and amounts earned from investing the contributions, less benefits paid. If a plan has liabilities other than for benefits, those non-benefit obligations may be considered as reductions of plan assets.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=35743120&loc=d3e1928-114920



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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 30

-Section 35

-Paragraph 50

-URI http://asc.fasb.org/extlink&oid=29635418&loc=d3e12355-114930

+ Details

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

X

- Definition

The amount of the cost recognized during the period for defined contribution plans.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 70

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6414718&loc=d3e28014-114942

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

X

- Definition

Percentage of employees' gross pay for which the employer contributes a matching contribution to a defined contribution plan.

+ References

No definition available.

+ Details

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

X

- Definition

Maximum percentage of employee gross pay the employee may contribute to a defined contribution plan.

+ References

No definition available.

+ Details

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

X

- Definition

Defined Benefit Plan Fair Value of Plan Assets Received from Acquisition

+ References

No definition available.

+ Details

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Namespace Prefix:	wex_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

X

- Definition

Defined Contribution Plan Employee Eligibility Age

+ References

No definition available.

+ Details

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Data Type:	xbrli:durationItemType
Balance Type:	na
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X

- Definition

Hours Of Service Eligible For Defined Contribution Plan

+ References

No definition available.

+ Details

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

X

- Definition

Number Of Years Of Service By Employee

+ References

No definition available.

+ Details

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

X

- Details

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

X

- Details

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