Other income (Schedule of Other Income) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Disaggregation of Revenue [Line Items]
Other income	$ 16.1	$ 23.3	$ 48.5	$ 57.5
Ancillary Product Profit Sharing [Member]
Disaggregation of Revenue [Line Items]
Other income	7.8	13.7	24.4	41.3
Interest [Member]
Disaggregation of Revenue [Line Items]
Other income	5.3	1.9	14.3	2.9
Remarketing Fees [Member]
Disaggregation of Revenue [Line Items]
Other income	2.5	7.1	8.2	11.0
Other [Member]
Disaggregation of Revenue [Line Items]
Other income	$ 0.5	$ 0.6	$ 1.6	$ 2.3