Revenues - Schedule of Contract with Customer, Asset and Liability (Details) - USD ($) $ in Millions	Sep. 30, 2026	Dec. 31, 2025
Location, Statement of Financial Position, Balance [Axis]: us-gaap:AccountsAndOtherReceivablesNetCurrent
Disaggregation of Revenue [Line Items]
Receivables	$ 61.1	$ 57.1
Location, Statement of Financial Position, Balance [Axis]: us-gaap:OtherAssetsNoncurrent
Disaggregation of Revenue [Line Items]
Contract assets	34.1	36.2
Location, Statement of Financial Position, Balance [Axis]: us-gaap:OtherLiabilitiesNoncurrent
Disaggregation of Revenue [Line Items]
Contract liabilities	48.9	64.8
Location, Statement of Financial Position, Balance [Axis]: us-gaap:PrepaidExpenseAndOtherAssetsCurrent
Disaggregation of Revenue [Line Items]
Contract assets	26.9	17.6
Location, Statement of Financial Position, Balance [Axis]: wex:AccruedExpensesAndOtherCurrentLiabilities
Disaggregation of Revenue [Line Items]
Contract liabilities	$ 28.2	$ 26.7

Amount, after allowance for credit loss, of right to consideration in exchange for good or service transferred to customer when right is conditioned on something other than passage of time, classified as current.

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