Off-Balance Sheet Arrangements (Details) - USD ($)	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
Accounts, Notes, Loans and Financing Receivable [Line Items]
Proceeds from sale of factoring receivables	$ 2,800,000,000	$ 2,000,000,000.0
Gain (loss) on sale of factoring receivables		(600,000)
WEX Europe Services
Accounts, Notes, Loans and Financing Receivable [Line Items]
Proceeds from sale of factoring receivables	128,800,000	150,000,000.0
WEX Latin America debt
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gain (loss) on sale of factoring receivables	3,700,000	3,700,000
WEX Latin America Securitization Facility \| WEX Latin America debt
Accounts, Notes, Loans and Financing Receivable [Line Items]
Proceeds from sale of factoring receivables	18,200,000	20,700,000
Equity contributions to investment fund	$ 0	$ 0

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- Definition

Amount of gain (loss) on sale of accounts receivable.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 20
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=118948506&loc=d3e107425-111719

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+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 12
-URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3179-108585

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+ References

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