Segment Information - Revenue by Segment (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Segment Reporting Information [Line Items]
Total revenues	$ 431,679	$ 381,876
Interest income	1,910	2,757
Fleet Solutions
Segment Reporting Information [Line Items]
Total revenues	249,847	232,782
Interest income	1,266	2,221
Travel and Corporate Solutions
Segment Reporting Information [Line Items]
Total revenues	84,359	81,648
Interest income	225	377
Health and Employee Benefit Solutions
Segment Reporting Information [Line Items]
Total revenues	97,473	67,446
Interest income	419	159
Payment processing revenue
Segment Reporting Information [Line Items]
Total revenues	204,037	186,798
Payment processing revenue | Fleet Solutions
Segment Reporting Information [Line Items]
Total revenues	113,323	107,408
Payment processing revenue | Travel and Corporate Solutions
Segment Reporting Information [Line Items]
Total revenues	70,268	59,998
Payment processing revenue | Health and Employee Benefit Solutions
Segment Reporting Information [Line Items]
Total revenues	20,446	19,392
Account servicing revenue
Segment Reporting Information [Line Items]
Total revenues	113,840	87,086
Account servicing revenue | Fleet Solutions
Segment Reporting Information [Line Items]
Total revenues	39,208	39,239
Account servicing revenue | Travel and Corporate Solutions
Segment Reporting Information [Line Items]
Total revenues	11,063	10,585
Account servicing revenue | Health and Employee Benefit Solutions
Segment Reporting Information [Line Items]
Total revenues	63,569	37,262
Finance fee revenue
Segment Reporting Information [Line Items]
Total revenues	55,927	46,373
Finance fee revenue | Fleet Solutions
Segment Reporting Information [Line Items]
Total revenues	55,342	45,864
Finance fee revenue | Travel and Corporate Solutions
Segment Reporting Information [Line Items]
Total revenues	535	357
Finance fee revenue | Health and Employee Benefit Solutions
Segment Reporting Information [Line Items]
Total revenues	50	152
Other revenue
Segment Reporting Information [Line Items]
Total revenues	57,875	61,619
Other revenue | Fleet Solutions
Segment Reporting Information [Line Items]
Total revenues	41,974	40,271
Other revenue | Travel and Corporate Solutions
Segment Reporting Information [Line Items]
Total revenues	2,493	10,708
Other revenue | Health and Employee Benefit Solutions
Segment Reporting Information [Line Items]
Total revenues	$ 13,408	$ 10,640