Redeemable Non-Controlling Interest - Schedule of Redeemable Non-Controlling Interest (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019
Increase (Decrease) in Temporary Equity [Roll Forward]
Balance, beginning of year	$ 156,879	$ 0
Acquisition of Discovery Benefits at fair value	0	25,757
Establishing redeemable non-controlling interest for WEX Health at carrying value	0	32,843
Adjustment to redeemable non-controlling interest to reflect WEX Health at fair value	0	41,400
Net income (loss) attributable to redeemable non-controlling interest	652	(436)
Change in value of redeemable non-controlling interest	(40,312)	57,315
Balance, end of year	$ 117,219	$ 156,879

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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- Definition

Amount of Net Income (Loss) attributable to redeemable noncontrolling interest.

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Amount of increase in noncontrolling interest from a business combination.

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Amount of increase in noncontrolling interest from subsidiary issuance of equity interests to noncontrolling interest holders.

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As of the reporting date, the aggregate carrying amount of all noncontrolling interests which are redeemable by the (parent) entity (1) at a fixed or determinable price on a fixed or determinable date, (2) at the option of the holder of the noncontrolling interest, or (3) upon occurrence of an event that is not solely within the control of the (parent) entity. This item includes noncontrolling interest holder's ownership (or holders' ownership) regardless of the type of equity interest (common, preferred, other) including all potential organizational (legal) forms of the investee entity.

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- Definition

Value of accretion of temporary equity to its redemption value during the period.

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Change in the value of each type or class of stock classified as temporary equity during the period. The redemption requirement does not constitute an unconditional obligation that will be settled in a variable number of shares constituting a monetary value predominantly indexed to (a) a fixed monetary amount known at inception, (b) an amount inversely correlated with the residual value of the entity, or (c) an amount determined by reference to something other than the fair value of issuer's stock. Does not include mandatorily redeemable stock. The exception is if redemption is required upon liquidation or termination of the reporting entity.

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