Loans Receivable (Summary of Changes In Allowance for Credit Losses) (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2016	Mar. 31, 2015
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of period		$ 243.6	$ 206.9
Provision for credit losses		22.1	6.2
Write-offs		(3.2)	(3.2)
Recoveries	[1],[2]	0.3	0.5
Balance, end of period		262.8	210.4
Dealer Loans [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of period		235.1	198.1
Provision for credit losses		21.8	6.2
Write-offs		(3.2)	(3.1)
Recoveries	[1],[2]	0.3	0.4
Balance, end of period		254.0	201.6
Purchased Loans [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of period		8.5	8.8
Provision for credit losses		0.3	0.0
Write-offs		0.0	(0.1)
Recoveries	[1],[2]	0.0	0.1
Balance, end of period		$ 8.8	$ 8.8

[1] Represents collections received on previously written off Loans.

[2] Represents collections received on previously written off Loans.