Summary Of Significant Accounting Policies (Schedule Of Other Income) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Summary Of Significant Accounting Policies [Line Items]
Other income	$ 40.2	$ 23.9	$ 24.6
Ancillary Product Profit Sharing Income [Member]
Summary Of Significant Accounting Policies [Line Items]
Other income	4.5	4.0	3.5
Dealer Support Products And Services [Member]
Summary Of Significant Accounting Policies [Line Items]
Other income	15.0	7.8	4.2
Vendor Fees [Member]
Summary Of Significant Accounting Policies [Line Items]
Other income	9.8	8.0	7.3
Dealer Enrollment Fees [Member]
Summary Of Significant Accounting Policies [Line Items]
Other income	8.3	3.4	7.8
Other [Member]
Summary Of Significant Accounting Policies [Line Items]
Other income	$ 2.6	$ 0.7	$ 1.8