Debt (Schedule of Additional Information Related to Debt Instruments) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Revolving Secured Line of Credit [Member]
Debt Instrument [Line Items]
Maximum outstanding balance	$ 355.5	$ 379.7	$ 355.5	$ 379.7
Average outstanding balance	162.5	242.7	142.9	144.6
Warehouse Facility II [Member]
Debt Instrument [Line Items]
Maximum outstanding balance	201.0	201.0	201.0	201.0
Average outstanding balance	59.6	167.9	39.4	88.8
Warehouse Facility IV [Member]
Debt Instrument [Line Items]
Maximum outstanding balance	0.0	43.8	0.0	43.8
Average outstanding balance	0.0	17.2	0.0	8.6
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	1.1	0.0	0.6
Warehouse Facility VIII [Member]
Debt Instrument [Line Items]
Maximum outstanding balance	0.0	48.2	0.0	48.2
Average outstanding balance	$ 0.0	$ 18.9	$ 0.0	$ 9.5