Debt (Scheduled Principal Maturities Of Debt) (Details) $ in Millions	Dec. 31, 2017 USD ($)
2017	$ 800.1
2018	1,015.6
2019	703.9
2020	323.4
2021	0.0
After 2021	250.0
Total	3,093.0
Revolving Secured Line Of Credit [Member]
2017	0.0
2018	0.0
2019	13.9
2020	0.0
2021	0.0
After 2021	0.0
Total	13.9
Secured Debt [Member]
2017	0.0
2018	0.0
2019	0.0
2020	0.0
2021	0.0
After 2021	0.0
Total	0.0
Term ABS Financing [Member]
2017	800.1	[1]
2018	1,015.6	[1]
2019	690.0	[1]
2020	23.4	[1]
2021	0.0	[1]
After 2021	0.0	[1]
Total	2,529.1	[1]
Senior Notes [Member]
2017	0.0
2018	0.0
2019	0.0
2020	300.0
2021	0.0
After 2021	250.0
Total	$ 550.0

[1] The principal maturities of the Term ABS transactions are estimated based on forecasted collections.