Debt (Summary Of Additional Information Of Credit facilities) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Revolving Secured Line Of Credit [Member]
Debt Instrument [Line Items]
Maximum outstanding balance	$ 282.9	$ 265.4
Average outstanding balance	77.2	40.6
Warehouse Facility II [Member]
Debt Instrument [Line Items]
Maximum outstanding balance	201.0	201.0
Average outstanding balance	78.0	3.3
Warehouse Facility IV [Member]
Debt Instrument [Line Items]
Maximum outstanding balance	100.0	99.0
Average outstanding balance	1.1	0.5
Warehouse Facility V [Member]
Debt Instrument [Line Items]
Maximum outstanding balance	35.0	99.0
Average outstanding balance	0.9	1.1
Warehouse Facility VI [Member]
Debt Instrument [Line Items]
Maximum outstanding balance	0.0	75.0
Average outstanding balance	0.0	0.4
Warehouse Facility VII [Member]
Debt Instrument [Line Items]
Maximum outstanding balance	101.5	150.0
Average outstanding balance	7.1	7.8
Warehouse Facility VIII [Member]
Debt Instrument [Line Items]
Maximum outstanding balance	145.3	0.0
Average outstanding balance	$ 7.2	$ 0.0