Summary Of Significant Accounting Policies (Schedule Of Other Income) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Summary Of Significant Accounting Policies [Line Items]
Other Income	$ 46.6	$ 40.8	$ 40.2
GPS-SID Fees [Member]
Summary Of Significant Accounting Policies [Line Items]
Other Income	16.4	12.8	14.4
Ancillary Product Profit Sharing [Member]
Summary Of Significant Accounting Policies [Line Items]
Other Income	11.9	11.1	8.3
Remarketing Fees [Member]
Summary Of Significant Accounting Policies [Line Items]
Other Income	6.9	6.2	5.2
Dealer Support Products And Services [Member]
Summary Of Significant Accounting Policies [Line Items]
Other Income	4.9	4.6	4.6
Dealer Enrollment Fees [Member]
Summary Of Significant Accounting Policies [Line Items]
Other Income	4.8	4.6	4.5
Other [Member]
Summary Of Significant Accounting Policies [Line Items]
Other Income	$ 1.7	$ 1.5	$ 3.2