v2.4.1.9

Fair Value - Assets and Liabilities Measured at Fair Value and Related Hierarchy Levels (Details) (USD $)
In Thousands, unless otherwise specified

Dec. 31, 2014

Dec. 31, 2013

Fair Value Measurements [Line Items]

Available-for-sale securities

$ 18,940us-gaap_AvailableForSaleSecurities

$ 15,963us-gaap_AvailableForSaleSecurities

Executive deferred compensation plan trust

5,927wex_DeferredCompensationPlanAssetsFairValue

^[1]

4,339wex_DeferredCompensationPlanAssetsFairValue

^[1]

Fuel price derivatives - liabilities

40,969us-gaap_PriceRiskDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsLiabilityAtFairValue

7,358us-gaap_PriceRiskDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsLiabilityAtFairValue

Mortgage-backed securities

Fair Value Measurements [Line Items]

Available-for-sale securities

810us-gaap_AvailableForSaleSecurities
/ us-gaap_FinancialInstrumentAxis
= us-gaap_MortgageBackedSecuritiesMember

839us-gaap_AvailableForSaleSecurities
/ us-gaap_FinancialInstrumentAxis
= us-gaap_MortgageBackedSecuritiesMember

Asset-backed securities

Fair Value Measurements [Line Items]

Available-for-sale securities

1,165us-gaap_AvailableForSaleSecurities
/ us-gaap_FinancialInstrumentAxis
= us-gaap_AssetBackedSecuritiesMember

1,391us-gaap_AvailableForSaleSecurities
/ us-gaap_FinancialInstrumentAxis
= us-gaap_AssetBackedSecuritiesMember

Municipal bonds

Fair Value Measurements [Line Items]

Available-for-sale securities

554us-gaap_AvailableForSaleSecurities
/ us-gaap_FinancialInstrumentAxis
= us-gaap_MunicipalBondsMember

519us-gaap_AvailableForSaleSecurities
/ us-gaap_FinancialInstrumentAxis
= us-gaap_MunicipalBondsMember

Equity securities

Fair Value Measurements [Line Items]

Available-for-sale securities

16,411us-gaap_AvailableForSaleSecurities
/ us-gaap_FinancialInstrumentAxis
= us-gaap_EquitySecuritiesMember

13,214us-gaap_AvailableForSaleSecurities
/ us-gaap_FinancialInstrumentAxis
= us-gaap_EquitySecuritiesMember

Fuel price derivatives - unleaded fuel

Fair Value Measurements [Line Items]

Fuel price derivatives - liabilities

29,120us-gaap_PriceRiskDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsLiabilityAtFairValue
/ us-gaap_FinancialInstrumentAxis
= wex_FuelPriceDerivativesUnleadedMember

^[2]

5,216us-gaap_PriceRiskDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsLiabilityAtFairValue
/ us-gaap_FinancialInstrumentAxis
= wex_FuelPriceDerivativesUnleadedMember

^[2]

Fuel price derivatives - diesel

Fair Value Measurements [Line Items]

Fuel price derivatives - liabilities

11,849us-gaap_PriceRiskDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsLiabilityAtFairValue
/ us-gaap_FinancialInstrumentAxis
= wex_FuelPriceDerivativesDieselMember

^[2]

2,142us-gaap_PriceRiskDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsLiabilityAtFairValue
/ us-gaap_FinancialInstrumentAxis
= wex_FuelPriceDerivativesDieselMember

^[2]

Quoted Prices in Active Markets for Identical Assets (Level 1)

Fair Value Measurements [Line Items]

Available-for-sale securities

16,411us-gaap_AvailableForSaleSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member

13,214us-gaap_AvailableForSaleSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member

Executive deferred compensation plan trust

5,927wex_DeferredCompensationPlanAssetsFairValue
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member

^[1]

4,339wex_DeferredCompensationPlanAssetsFairValue
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member

^[1]

Quoted Prices in Active Markets for Identical Assets (Level 1) | Equity securities

Fair Value Measurements [Line Items]

Available-for-sale securities

16,411us-gaap_AvailableForSaleSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member
/ us-gaap_FinancialInstrumentAxis
= us-gaap_EquitySecuritiesMember

13,214us-gaap_AvailableForSaleSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member
/ us-gaap_FinancialInstrumentAxis
= us-gaap_EquitySecuritiesMember

Significant Other Observable Inputs (Level 2)

Fair Value Measurements [Line Items]

Available-for-sale securities

2,529us-gaap_AvailableForSaleSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member

2,749us-gaap_AvailableForSaleSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member

Fuel price derivatives - liabilities

29,120us-gaap_PriceRiskDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsLiabilityAtFairValue
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member

5,216us-gaap_PriceRiskDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsLiabilityAtFairValue
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member

Significant Other Observable Inputs (Level 2) | Mortgage-backed securities

Fair Value Measurements [Line Items]

Available-for-sale securities

810us-gaap_AvailableForSaleSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
/ us-gaap_FinancialInstrumentAxis
= us-gaap_MortgageBackedSecuritiesMember

839us-gaap_AvailableForSaleSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
/ us-gaap_FinancialInstrumentAxis
= us-gaap_MortgageBackedSecuritiesMember

Significant Other Observable Inputs (Level 2) | Asset-backed securities

Fair Value Measurements [Line Items]

Available-for-sale securities

1,165us-gaap_AvailableForSaleSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
/ us-gaap_FinancialInstrumentAxis
= us-gaap_AssetBackedSecuritiesMember

1,391us-gaap_AvailableForSaleSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
/ us-gaap_FinancialInstrumentAxis
= us-gaap_AssetBackedSecuritiesMember

Significant Other Observable Inputs (Level 2) | Municipal bonds

Fair Value Measurements [Line Items]

Available-for-sale securities

554us-gaap_AvailableForSaleSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
/ us-gaap_FinancialInstrumentAxis
= us-gaap_MunicipalBondsMember

519us-gaap_AvailableForSaleSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
/ us-gaap_FinancialInstrumentAxis
= us-gaap_MunicipalBondsMember

Significant Other Observable Inputs (Level 2) | Fuel price derivatives - unleaded fuel

Fair Value Measurements [Line Items]

Fuel price derivatives - liabilities

29,120us-gaap_PriceRiskDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsLiabilityAtFairValue
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
/ us-gaap_FinancialInstrumentAxis
= wex_FuelPriceDerivativesUnleadedMember

^[2]

5,216us-gaap_PriceRiskDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsLiabilityAtFairValue
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
/ us-gaap_FinancialInstrumentAxis
= wex_FuelPriceDerivativesUnleadedMember

^[2]

Significant Other Observable Inputs (Level 3)

Fair Value Measurements [Line Items]

Fuel price derivatives - liabilities

11,849us-gaap_PriceRiskDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsLiabilityAtFairValue
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member

2,142us-gaap_PriceRiskDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsLiabilityAtFairValue
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member

Significant Other Observable Inputs (Level 3) | Fuel price derivatives - diesel

Fair Value Measurements [Line Items]

Fuel price derivatives - liabilities

$ 11,849us-gaap_PriceRiskDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsLiabilityAtFairValue
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FinancialInstrumentAxis
= wex_FuelPriceDerivativesDieselMember

^[2]

$ 2,142us-gaap_PriceRiskDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsLiabilityAtFairValue
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FinancialInstrumentAxis
= wex_FuelPriceDerivativesDieselMember

^[2]

[1]	The fair value of these instruments is recorded in other assets.
[2]	The consolidated balance sheet presentation combines unleaded fuel and diesel fuel positions.

X

- Definition

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 25

-Paragraph 1

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=28360136&loc=d3e22054-111558



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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 50

-Paragraph 5

-Subparagraph (aa)

-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27232-111563



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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 45

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6871852&loc=d3e26610-111562

+ Details

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

X

- Definition

Fair value as of the balance sheet date of all price risk derivative liabilities not designated as hedging instruments.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 4B

-Subparagraph (c)(2)

-URI http://asc.fasb.org/extlink&oid=35706170&loc=SL5624163-113959

+ Details

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

X

- Definition

Deferred compensation plan assets fair value.

+ References

No definition available.

+ Details

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

X

- Details

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Namespace Prefix:	wex_
Data Type:	xbrli:stringItemType
Balance Type:	na
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X

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Balance Type:
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X

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_AssetBackedSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_EquitySecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_MortgageBackedSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_MunicipalBondsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FinancialInstrumentAxis=wex_FuelPriceDerivativesDieselMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FinancialInstrumentAxis=wex_FuelPriceDerivativesUnleadedMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: