Loans Receivable (Summary of Changes in Accretable Yield) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2014		Sep. 30, 2013		Sep. 30, 2014		Sep. 30, 2013
Certain Loans Acquired in Transfer Not Accounted for as Loans Accretable Yield Movement Schedule [Roll Forward]
Balance, beginning of period	$ 834.1		$ 766.1		$ 780.3		$ 718.1
New Consumer Loan assignments	155.6	[1]	151.8	[1]	499.7	[1]	474.1	[1]
Finance charge income	(158.0)		(148.7)		(468.7)		(439.1)
Forecast changes	9.8		9.0		27.6		23.0
Transfers	1.2	[2]	1.5	[2]	3.8	[2]	3.6	[2]
Balance, end of period	842.7		779.7		842.7		779.7
Dealer Loans [Member]
Certain Loans Acquired in Transfer Not Accounted for as Loans Accretable Yield Movement Schedule [Roll Forward]
Balance, beginning of period	709.6		654.8		667.5		602.9
New Consumer Loan assignments	137.7	[1]	138.1	[1]	445.2	[1]	437.1	[1]
Finance charge income	(138.6)		(131.0)		(411.7)		(384.5)
Forecast changes	7.3		7.6		19.0		17.7
Transfers	(1.1)	[2]	(1.9)	[2]	(5.1)	[2]	(5.6)	[2]
Balance, end of period	714.9		667.6		714.9		667.6
Purchased Loans [Member]
Certain Loans Acquired in Transfer Not Accounted for as Loans Accretable Yield Movement Schedule [Roll Forward]
Balance, beginning of period	124.5		111.3		112.8		115.2
New Consumer Loan assignments	17.9	[1]	13.7	[1]	54.5	[1]	37.0	[1]
Finance charge income	(19.4)		(17.7)		(57.0)		(54.6)
Forecast changes	2.5		1.4		8.6		5.3
Transfers	2.3	[2]	3.4	[2]	8.9	[2]	9.2	[2]
Balance, end of period	$ 127.8		$ 112.1		$ 127.8		$ 112.1

[1] The Dealer Loans amount represents the net cash flows expected at the time of assignment on Consumer Loans assigned under our Portfolio Program, less the related advances paid to Dealers. The Purchased Loans amount represents the net cash flows expected at the time of assignment on Consumer Loans assigned under our Purchase Program, less the related one-time payments made to Dealers.

[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 and related expected future net cash flows to Purchased Loans in the period this forfeiture occurs.