Finance Receivables Finance Receivables Summary (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		12 Months Ended
	Dec. 31, 2010	Sep. 30, 2010	Dec. 31, 2012	Dec. 31, 2011	Jun. 30, 2010	Jun. 30, 2009
Consumer Loans Auto Financing Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Pre-Acquisition Finance Receivables, Carrying Value	$ 7,299,963	$ 8,230,743	$ 1,958,204	$ 4,027,361	$ 8,733,518	$ 10,927,969
Post-Acquisition Finance Receivables, Carrying Value	923,713		8,830,914	5,313,899
Finance Receivables Purchased	934,812	959,004	5,578,839	5,084,800	2,137,620
Financing Receivable, Allowance for Credit Losses, Charge-offs		(217,520)	(304,293)	(66,080)	(1,249,298)
Change in Carrying Value Adjustment	(177,996)		(169,680)	(483,048)
Principal Collection and Recoveries on Receivables	(763,883)	(799,427)	(3,657,008)	(3,418,088)	(3,082,773)
Financing Receivable, Gross	8,223,676	8,675,575	10,789,118	9,341,260	8,733,518
Commercial Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Finance Receivables Purchased			1,227,287
Principal Collection and Recoveries on Receivables			(667,288)
Financing Receivable, Gross			$ 559,999