Debt (Schedule of Additional Information Related to Debt Instruments) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Revolving Secured Line of Credit [Member]
Debt Instrument [Line Items]
Maximum outstanding balance	$ 302.2	$ 356.3	$ 355.5	$ 379.7
Average outstanding balance	171.1	169.1	152.4	152.8
Warehouse Facility II [Member]
Debt Instrument [Line Items]
Maximum outstanding balance	201.0	100.0	201.0	201.0
Average outstanding balance	86.2	71.7	55.2	83.1
Warehouse Facility IV [Member]
Debt Instrument [Line Items]
Maximum outstanding balance	0.0	0.0	0.0	43.8
Average outstanding balance	0.0	0.0	0.0	5.7
Warehouse Facility V [Member]
Debt Instrument [Line Items]
Maximum outstanding balance	0.0	0.0	0.0	0.0
Average outstanding balance	0.0	0.0	0.0	0.0
Warehouse Facility VI [Member]
Debt Instrument [Line Items]
Maximum outstanding balance	0.0	50.0	0.0	50.0
Average outstanding balance	0.0	50.0	0.0	17.2
Warehouse Facility VIII [Member]
Debt Instrument [Line Items]
Maximum outstanding balance	0.0	0.0	0.0	48.2
Average outstanding balance	$ 0.0	$ 0.0	$ 0.0	$ 6.3