Other Income (Disaggregation of Revenue) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Disaggregation of Revenue [Line Items]
Other income	$ 17.6	$ 16.1	$ 50.7	$ 48.5
Transferred over Time [Member]
Disaggregation of Revenue [Line Items]
Other income	14.5		40.8
Transferred at Point in Time [Member]
Disaggregation of Revenue [Line Items]
Other income	3.1		9.9
Third Party Providers [Member]
Disaggregation of Revenue [Line Items]
Other income	14.4		40.5
Dealers [Member]
Disaggregation of Revenue [Line Items]
Other income	3.2		10.2
Ancillary Product Profit Sharing [Member]
Disaggregation of Revenue [Line Items]
Other income	8.0	7.8	21.7	24.4
Ancillary Product Profit Sharing [Member] \| Transferred over Time [Member]
Disaggregation of Revenue [Line Items]
Other income	8.0		21.7
Ancillary Product Profit Sharing [Member] \| Transferred at Point in Time [Member]
Disaggregation of Revenue [Line Items]
Other income	0.0		0.0
Ancillary Product Profit Sharing [Member] \| Third Party Providers [Member]
Disaggregation of Revenue [Line Items]
Other income	8.0		21.7
Ancillary Product Profit Sharing [Member] \| Dealers [Member]
Disaggregation of Revenue [Line Items]
Other income	0.0		0.0
Interest [Member]
Disaggregation of Revenue [Line Items]
Other income	6.4	5.3	18.6	14.3
Interest [Member] \| Transferred over Time [Member]
Disaggregation of Revenue [Line Items]
Other income	6.4		18.6
Interest [Member] \| Transferred at Point in Time [Member]
Disaggregation of Revenue [Line Items]
Other income	0.0		0.0
Interest [Member] \| Third Party Providers [Member]
Disaggregation of Revenue [Line Items]
Other income	6.4		18.6
Interest [Member] \| Dealers [Member]
Disaggregation of Revenue [Line Items]
Other income	0.0		0.0
Remarketing Fees [Member]
Disaggregation of Revenue [Line Items]
Other income	2.9	2.5	9.1	8.2
Remarketing Fees [Member] \| Transferred over Time [Member]
Disaggregation of Revenue [Line Items]
Other income	0.0		0.0
Remarketing Fees [Member] \| Transferred at Point in Time [Member]
Disaggregation of Revenue [Line Items]
Other income	2.9		9.1
Remarketing Fees [Member] \| Third Party Providers [Member]
Disaggregation of Revenue [Line Items]
Other income	0.0		0.0
Remarketing Fees [Member] \| Dealers [Member]
Disaggregation of Revenue [Line Items]
Other income	2.9		9.1
Other [Member]
Disaggregation of Revenue [Line Items]
Other income	0.3	$ 0.5	1.3	$ 1.6
Other [Member] \| Transferred over Time [Member]
Disaggregation of Revenue [Line Items]
Other income	0.1		0.5
Other [Member] \| Transferred at Point in Time [Member]
Disaggregation of Revenue [Line Items]
Other income	0.2		0.8
Other [Member] \| Third Party Providers [Member]
Disaggregation of Revenue [Line Items]
Other income	0.0		0.2
Other [Member] \| Dealers [Member]
Disaggregation of Revenue [Line Items]
Other income	$ 0.3		$ 1.1