Related Party Transactions (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014		Mar. 31, 2013		Dec. 31, 2013
Related Party Transaction [Line Items]
Affiliated Dealer Loan balances	$ 7.8				$ 7.5
Percentage of Affiliated Dealer Loan balances	0.30%				0.30%
New Consumer Loan assignments	421.3		378.6
Accelerated Dealer Holdback payments	(11.2)		(9.5)
Dealer Holdback payments	34.5		30.0
Affiliated Dealer Activity [Member]
Related Party Transaction [Line Items]
Dealer Loan revenue	0.4		0.3
Dealer Loan revenue, percentage	0.30%		0.20%
New Consumer Loan assignments	1.1	[1]	1.1	[1]
New Consumer Loan assignments, percentage	0.20%	[1]	0.30%	[1]
Accelerated Dealer Holdback payments, percentage	0.00%		0.30%
Dealer Holdback payments	$ 0.4		$ 0.6
Dealer Holdback payments, percentage	1.20%		2.00%

[1] Represents advances paid to Dealers on Consumer Loans assigned under our Portfolio Program and one-time payments made to Dealers to purchase Consumer Loans assigned under our Purchase Program.