Related Party Transactions (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011
Related Party Transaction [Line Items]
Affiliated Dealer Loan balances	$ 7.5		$ 5.9
Percentage of Affiliated Dealer Loan balances	0.30%		0.30%		0.30%
New Consumer Loan assignments	1,356.6		1,253.6		1,152.5
Accelerated Dealer Holdback payments	(40.4)		(43.7)		(47.4)
Dealer Holdback payments	114.2		115.7		85.2
Affiliated Dealer Activity [Member]
Related Party Transaction [Line Items]
Dealer Loan revenue	1.5		1.2		1.6
New Consumer Loan assignments	4.3	[1]	3.6	[1]	1.3	[1]
Accelerated Dealer Holdback payments	0.1		0.1
Dealer Holdback payments	$ 2.2		$ 3.2		$ 2.4
% Of Consolidated [Member]
Related Party Transaction [Line Items]
Dealer Loan revenue, percentage	0.30%		0.30%		0.40%
New Consumer Loan assignments, percentage	0.30%	[1]	0.30%	[1]	0.10%	[1]
Accelerated Dealer Holdback payments, percentage	0.20%		0.20%		0.10%
Dealer Holdback payments, percentage	1.90%		2.80%		2.80%

[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.