Consolidated Statements Of Cash Flows (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011
Cash Flows From Operating Activities:
Net income	$ 159,839	$ 137,995
Adjustments to reconcile cash provided by operating activities:
Provision for credit losses	17,716	22,394
Depreciation	3,690	3,076
Amortization	5,126	4,346
Loss on retirement of property and equipment	10	28
Provision for deferred income taxes	11,884	8,763
Stock-based compensation	8,601	1,556
Change in operating assets and liabilities:
Increase in accounts payable and accrued liabilities	2,273	15,951
Decrease in income taxes receivable	506	11,503
Increase in income taxes payable	8,498	448
Decrease (increase) in other assets	367	(3,703)
Net cash provided by operating activities	218,510	202,357
Cash Flows From Investing Activities:
Increase in restricted cash and cash equivalents	(63,027)	(24,676)
Purchases of restricted securities available for sale	(100)	(532)
Proceeds from sale of restricted securities available for sale	905	76
Maturities of restricted securities available for sale	0	454
Principal collected on Loans receivable	882,613	748,242
Advances to Dealers	(968,725)	(888,602)
Purchases of Consumer Loans	(85,992)	(94,212)
Accelerated payments of Dealer Holdback	(34,107)	(37,275)
Payments of Dealer Holdback	(89,734)	(58,734)
Net decrease in other loans	84	797
Purchases of property and equipment	(7,091)	(3,569)
Net cash used in investing activities	(365,174)	(358,031)
Cash Flows From Financing Activities:
Borrowings under revolving secured line of credit	1,969,700	1,757,500
Repayments under revolving secured line of credit	(1,897,800)	(1,794,800)
Proceeds from secured financing	1,426,650	600,000
Repayments of secured financing	(1,234,081)	(385,293)
Principal payments under mortgage note	(184)	(175)
Proceeds from sale of senior notes	0	106,000
Payments of debt issuance costs	(5,973)	(6,849)
Repurchase of common stock	(112,946)	(126,675)
Proceeds from stock options exercised	519	2,781
Tax benefits from stock-based compensation plans	1,847	3,027
Net cash provided by financing activities	147,732	155,516
Net increase (decrease) in cash and cash equivalents	1,068	(158)
Cash and cash equivalents, beginning of period	4,657	3,792
Cash and cash equivalents, end of period	5,725	3,634
Supplemental Disclosure of Cash Flow Information:
Cash paid during the period for interest	49,790	37,677
Cash paid during the period for income taxes	$ 68,902	$ 55,116