Consolidated Statements of Cash Flows (Unaudited) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Cash Flows From Operating Activities:
Net income	$ 71.5	$ 49.8
Adjustments to reconcile cash provided by operating activities:
Provision for credit losses	6.2	4.7
Depreciation	1.5	1.3
Amortization	2.2	1.7
Loss on retirement of property and equipment	0.1	0
Provision for deferred income taxes	7.0	27.7
Loss on extinguishment of debt	0	21.8
Stock-based compensation	4.1	4.4
Change in operating assets and liabilities:
Increase (decrease) in accounts payable and accrued liabilities	7.9	(2.4)
Decrease (increase) in income taxes receivable	0.4	(0.9)
Increase (decrease) in income taxes payable	13.0	(15.7)
Decrease in other assets	3.5	1.1
Net cash provided by operating activities	117.4	93.5
Cash Flows From Investing Activities:
Increase in restricted cash and cash equivalents	(41.3)	(35.3)
Purchases of restricted securities available for sale	(11.6)	(15.2)
Proceeds from sale of restricted securities available for sale	11.5	2.1
Maturities of restricted securities available for sale	0.5	14.5
Principal collected on Loans receivable	454.5	408.2
Advances to Dealers	(533.5)	(421.3)
Purchases of Consumer Loans	(92.6)	(51.1)
Accelerated payments of Dealer Holdback	(13.8)	(11.2)
Payments of Dealer Holdback	(41.1)	(34.5)
Purchases of property and equipment	(1.3)	(2.1)
Net cash used in investing activities	(268.7)	(145.9)
Cash Flows From Financing Activities:
Borrowings under revolving secured line of credit	988.4	525.1
Repayments under revolving secured line of credit	(1,107.9)	(512.0)
Proceeds from secured financing	535.4	360.6
Repayments of secured financing	(433.1)	(157.6)
Proceeds from issuance of senior notes	248.2	300.0
Repayment of senior notes	0	(350.0)
Payments of debt issuance and debt extinguishment costs	(6.2)	(22.8)
Repurchase of common stock	(1.1)	(103.6)
Proceeds from stock options exercised	0	0.6
Tax benefits from stock-based compensation plans	0.3	13.6
Proceeds from (Payments for) Other Financing Activities	7.6	(0.1)
Net cash provided by financing activities	231.6	53.8
Net increase in cash and cash equivalents	80.3	1.4
Cash and cash equivalents, beginning of period	6.4
Cash and cash equivalents, end of period	86.7	5.6
Supplemental Disclosure of Cash Flow Information:
Cash paid during the period for interest	17.3	23.8
Cash paid during the period for income taxes	$ 20.2	$ 5.5