CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Statement of Comprehensive Income [Abstract]
Net income	$ 95.3	$ 34.1	$ 163.3	$ 122.9
Other comprehensive income (loss), net of tax:
Unrealized losses on available-for-sale debt securities	(29.9)	(42.1)	(7.7)	(93.7)
Foreign currency translation	5.5	(45.7)	6.3	(41.4)
Other comprehensive income (loss), net of tax	(24.4)	(87.8)	(1.4)	(135.2)
Comprehensive income (loss)	70.9	(53.7)	161.9	(12.3)
Less: Comprehensive income attributable to non-controlling interests	0.0	0.0	0.0	0.3
Comprehensive income (loss) attributable to WEX Inc.	$ 70.9	$ (53.7)	$ 161.9	$ (12.5)