Debt (Summary Of Additional Information Of Credit facilities) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Revolving Secured Line Of Credit [Member]
Debt Instrument [Line Items]
Maximum outstanding balance	$ 186.4	$ 206.3
Average outstanding balance	30.8	39.1
Warehouse Facility II [Member]
Debt Instrument [Line Items]
Maximum outstanding balance	200.1	200.8
Average outstanding balance	3.8	7.9
Warehouse Facility IV [Member]
Debt Instrument [Line Items]
Maximum outstanding balance	12.0	35.0
Average outstanding balance	12.0	9.2
Warehouse Facility V [Member]
Debt Instrument [Line Items]
Maximum outstanding balance	100.0	99.2
Average outstanding balance	1.6	12.2
Warehouse Facility VI [Member]
Debt Instrument [Line Items]
Maximum outstanding balance	49.9	15.0
Average outstanding balance	$ 3.3	$ 1.5