Securitization Notes Payable (Details) (USD $) In Thousands, unless otherwise specified			9 Months Ended
	Sep. 30, 2012	Dec. 31, 2011	Sep. 30, 2012 2008 Transactions [Member] Rate	Sep. 30, 2012 2009 Transactions [Member] Rate	Sep. 30, 2012 2010 Transactions [Member] Rate	Sep. 30, 2012 2011 Transactions [Member] Rate	Sep. 30, 2012 2012 Transactions [Member] Rate
Debt Instrument, Maturity Date Range, Start			Oct. 01, 2014	Jan. 01, 2016	Jul. 01, 2017	Jul. 01, 2018	Jun. 01, 2019
Secured Debt			$ 104,823	$ 188,389	$ 1,234,762	$ 2,797,680	$ 4,662,831
Debt Instrument, Unamortized Premium	16,718
Securitized Debt Obligation Liability	9,005,203	6,937,841
Debt Instrument, Maturity Date Range, End			Apr. 01, 2015	Jul. 01, 2017	Apr. 01, 2018	Mar. 01, 2019	Feb. 01, 2020
Original Note Amounts - Minimum			500,000	227,493	200,000	800,000	800,000
Original Note Amounts - Maximum			750,000	725,000	850,000	1,000,000	1,300,000
Original Weighted-Average Interest Rate - Minimum			6.00%	2.70%	2.20%	2.40%	1.50%
Original Weighted-Average Interest Rate - Maximum			10.50%	7.50%	3.80%	2.90%	2.90%
Finance Receivables Transferred to Special Purpose Entities	9,937,604		281,734	250,771	1,394,077	3,037,396	4,973,626
Securitized Debt Obligation Liability - Gross	$ 8,988,485