Other income (Schedule of Other Income) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Disaggregation of Revenue [Line Items]
Other income	$ 17.1	$ 16.4	$ 32.4	$ 34.2
Ancillary Product Profit Sharing [Member]
Disaggregation of Revenue [Line Items]
Other income	9.1	12.9	16.6	27.6
Remarketing Fees [Member]
Disaggregation of Revenue [Line Items]
Other income	2.7	1.9	5.7	3.9
Interest [Member]
Disaggregation of Revenue [Line Items]
Other income	4.9	0.7	9.0	1.0
Other [Member]
Disaggregation of Revenue [Line Items]
Other income	$ 0.4	$ 0.9	$ 1.1	$ 1.7