Debt (Schedule of Additional Information Related to Debt Instruments) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Revolving Secured Line of Credit [Member]
Debt Instrument [Line Items]
Maximum outstanding balance	$ 356.3	$ 72.2	$ 379.7	$ 216.0
Average outstanding balance	169.1	1.5	152.8	26.9
Warehouse Facility II [Member]
Debt Instrument [Line Items]
Maximum outstanding balance	100.0	0.0	201.0	201.0
Average outstanding balance	71.7	0.0	83.1	15.6
Warehouse Facility IV [Member]
Debt Instrument [Line Items]
Maximum outstanding balance	0.0	0.0	43.8	0.0
Average outstanding balance	0.0	0.0	5.7	0.0
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	50.0	0.0	50.0	0.0
Average outstanding balance	50.0	0.0	17.2	0.0
Warehouse Facility VIII [Member]
Debt Instrument [Line Items]
Maximum outstanding balance	0.0	0.0	48.2	0.0
Average outstanding balance	$ 0.0	$ 0.0	$ 6.3	$ 0.0