Segment Information - Revenue by Segment (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Segment Reporting Information [Line Items]
Total revenues	$ 621.3	$ 598.2	$ 1,233.3	$ 1,115.8
Mobility
Segment Reporting Information [Line Items]
Total revenues	340.2	379.2	682.5	698.4
Corporate Payments
Segment Reporting Information [Line Items]
Total revenues	121.9	100.4	226.7	177.7
Benefits
Segment Reporting Information [Line Items]
Total revenues	159.2	118.6	324.1	239.7
Payment processing revenue
Segment Reporting Information [Line Items]
Total revenues	300.5	312.3	588.6	551.8
Payment processing revenue | Mobility
Segment Reporting Information [Line Items]
Total revenues	172.2	202.4	343.7	354.3
Payment processing revenue | Corporate Payments
Segment Reporting Information [Line Items]
Total revenues	104.7	88.6	194.8	153.7
Payment processing revenue | Benefits
Segment Reporting Information [Line Items]
Total revenues	23.6	21.3	50.1	43.8
Account servicing revenue
Segment Reporting Information [Line Items]
Total revenues	152.9	137.6	313.6	277.6
Account servicing revenue | Mobility
Segment Reporting Information [Line Items]
Total revenues	40.8	43.9	81.1	86.3
Account servicing revenue | Corporate Payments
Segment Reporting Information [Line Items]
Total revenues	10.6	10.4	21.2	21.2
Account servicing revenue | Benefits
Segment Reporting Information [Line Items]
Total revenues	101.5	83.4	211.3	170.1
Finance fee revenue
Segment Reporting Information [Line Items]
Total revenues	76.4	85.3	157.1	163.9
Finance fee revenue | Mobility
Segment Reporting Information [Line Items]
Total revenues	76.3	85.1	156.7	163.5
Finance fee revenue | Corporate Payments
Segment Reporting Information [Line Items]
Total revenues	0.1	0.2	0.3	0.4
Finance fee revenue | Benefits
Segment Reporting Information [Line Items]
Total revenues	0.0	0.0	0.1	0.1
Other revenue
Segment Reporting Information [Line Items]
Total revenues	91.5	63.0	174.0	122.5
Other revenue | Mobility
Segment Reporting Information [Line Items]
Total revenues	50.9	47.9	101.0	94.3
Other revenue | Corporate Payments
Segment Reporting Information [Line Items]
Total revenues	6.5	1.2	10.4	2.5
Other revenue | Benefits
Segment Reporting Information [Line Items]
Total revenues	$ 34.1	$ 13.9	$ 62.6	$ 25.7