Loans Receivable (Summary Of Changes In Loans Receivable) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Accounts, Notes, Loans and Financing Receivable [Line Items]
Balance, beginning of period	$ 2,408.2		$ 2,109.9		$ 1,752.9
New Consumer Loan assignments	1,675.7	[1]	1,480.6	[1]	1,362.4	[1]
Principal collected on Loans receivable	(1,540.1)		(1,334.4)		(1,162.8)
Accelerated Dealer Holdback payments	(41.7)		(40.4)		(43.7)
Dealer Holdback payments	135.5		114.2		115.7
Transfers	0	[2]	0	[2]	0	[2]
Write-offs	(3.2)		(5.3)		(4.2)
Recoveries	1.9	[3]	2.4	[3]	2.3	[3]
Net change in other loans	0.1		0.4		(0.1)
Balance, end of period	2,719.8		2,408.2		2,109.9
Dealer Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Balance, beginning of period	2,155.5		1,869.4		1,506.5
New Consumer Loan assignments	1,471.4	[1]	1,356.6	[1]	1,253.6	[1]
Principal collected on Loans receivable	(1,392.6)		(1,204.6)		(1,024.8)
Accelerated Dealer Holdback payments	(41.7)		(40.4)		(43.7)
Dealer Holdback payments	135.5		114.2		115.7
Transfers	(20.5)	[2]	(17.9)	[2]	(23.8)	[2]
Write-offs	(3.1)		(5.2)		(3.6)
Recoveries	1.8	[3]	2.2	[3]	2.2	[3]
Net change in other loans	0.1		0.4		(0.1)
Balance, end of period	2,389.8		2,155.5		1,869.4
Purchased Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Balance, beginning of period	252.7		240.5		246.4
New Consumer Loan assignments	204.3	[1]	124.0	[1]	108.8	[1]
Principal collected on Loans receivable	(147.5)		(129.8)		(138.0)
Accelerated Dealer Holdback payments	0		0		0
Dealer Holdback payments	0		0		0
Transfers	20.5	[2]	17.9	[2]	23.8	[2]
Write-offs	(0.1)		(0.1)		(0.6)
Recoveries	0.1	[3]	0.2	[3]	0.1	[3]
Net change in other loans	0		0		0
Balance, end of period	$ 330.0		$ 252.7		$ 240.5

[1] The Dealer Loans amount represents advances paid to Dealers on Consumer Loans assigned under our Portfolio Program. The Purchased Loans amount represents one-time payments made to Dealers to purchase Consumer Loans assigned under our Purchase Program.

[2] Under our Portfolio Program, certain events may result in Dealers forfeiting their rights to Dealer Holdback. We transfer the Dealer’s outstanding Dealer Loan balance to Purchased Loans in the period this forfeiture occurs.

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