Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Cash Flows From Operating Activities:
Net income	$ 271.1	$ 192.4
Adjustments to reconcile cash provided by operating activities:
Provision for credit losses	25.2	42.3
Depreciation	2.6	3.2
Amortization	6.3	5.1
Loss on retirement of property and equipment	0.0	0.1
Provision for deferred income taxes	38.9	51.5
Stock-based compensation	5.1	5.4
Change in operating assets and liabilities:
Increase (decrease) in accounts payable and accrued liabilities	22.7	(8.7)
Increase in income taxes receivable	(23.4)	(6.1)
Decrease in income taxes payable	(39.7)	(23.4)
Decrease (increase) in other assets	1.2	(0.8)
Net cash provided by operating activities	310.0	261.0
Cash Flows From Investing Activities:
Purchases of restricted securities available for sale	(28.4)	(21.6)
Proceeds from sale of restricted securities available for sale	13.0	16.7
Maturities of restricted securities available for sale	6.4	3.8
Principal collected on Loans receivable	1,301.7	1,116.3
Advances to Dealers	(1,313.5)	(993.2)
Purchases of Consumer Loans	(642.7)	(470.1)
Accelerated payments of Dealer Holdback	(29.4)	(23.6)
Payments of Dealer Holdback	(66.1)	(68.7)
Purchases of property and equipment	(5.2)	(5.1)
Net cash used in investing activities	(764.2)	(445.5)
Cash Flows From Financing Activities:
Borrowings under revolving secured line of credit	1,433.2	2,523.6
Repayments under revolving secured line of credit	(1,447.1)	(2,523.6)
Proceeds from secured financing	1,900.0	1,664.5
Repayments of secured financing	(1,288.8)	(1,251.4)
Payments of debt issuance costs	(9.3)	(8.5)
Repurchase of common stock	(2.0)	(123.5)
Other financing activities	(1.9)	5.2
Net cash provided by financing activities	584.1	286.3
Net increase in cash, cash equivalents, restricted cash and restricted cash equivalents	129.9	101.8
Cash, cash equivalents, restricted cash and restricted cash equivalents beginning of period	263.8	239.3
Cash, cash equivalents, restricted cash and restricted cash equivalents end of period	393.7	341.1
Supplemental Disclosure of Cash Flow Information:
Cash paid during the period for interest	65.8	52.0
Cash paid during the period for income taxes	$ 105.7	$ 85.7