Other income (Schedule of Other Income) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Disaggregation of Revenue [Line Items]
Other Income	$ 83.4	$ 53.1	$ 49.6
Ancillary Product Profit Sharing [Member]
Disaggregation of Revenue [Line Items]
Other Income	60.6	40.2	33.5
Remarketing Fees [Member]
Disaggregation of Revenue [Line Items]
Other Income	13.4	7.8	7.1
Dealer Enrollment Fees [Member]
Disaggregation of Revenue [Line Items]
Other Income	1.7	1.9	3.0
Dealer Support Products And Services [Member]
Disaggregation of Revenue [Line Items]
Other Income	1.2	1.3	1.9
Interest Income [Member]
Disaggregation of Revenue [Line Items]
Other Income	6.6	1.2	2.9
Other [Member]
Disaggregation of Revenue [Line Items]
Other Income	$ (0.1)	$ 0.7	$ 1.2