Debt (Summary Of Additional Information Of Credit facilities) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Revolving Secured Line Of Credit [Member]
Debt Instrument [Line Items]
Maximum outstanding balance	$ 265.4	$ 276.7
Average outstanding balance	40.6	80.3
Warehouse Facility II [Member]
Debt Instrument [Line Items]
Maximum outstanding balance	201.0	275.0
Average outstanding balance	3.3	4.0
Warehouse Facility IV [Member]
Debt Instrument [Line Items]
Maximum outstanding balance	99.0	12.0
Average outstanding balance	0.5	5.9
Warehouse Facility V [Member]
Debt Instrument [Line Items]
Maximum outstanding balance	99.0	100.0
Average outstanding balance	1.1	7.8
Warehouse Facility VI [Member]
Debt Instrument [Line Items]
Maximum outstanding balance	75.0	75.0
Average outstanding balance	0.4	7.8
Warehouse Facility VII [Member]
Debt Instrument [Line Items]
Maximum outstanding balance	150.0	0.0
Average outstanding balance	$ 7.8	$ 0.0