Fair Value Of Financial Instruments (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013		Mar. 31, 2013	Dec. 31, 2012		Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Dealer Finance Receivables - GO, net	$ 92,278		$ 74,753	$ 40,956		$ 11,633	$ 5,473	$ 24
Portfolio Term Financings	1,108,796			1,049,478
Portfolio Warehouse Facilities	78,000			57,200
Senior Secured Notes Payable	248,766			193,320
Other Secured Notes Payable	136,016			117,281
Securitization Debt [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Portfolio Term Financings	720,967			677,118
Portfolio Term Residual Financing [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Portfolio Term Financings	100,000			25,000
Bank Term Financings [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Portfolio Term Financings	287,829			347,360
Revolving Inventory Facility [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other Secured Notes Payable	111,321			91,320
Mortgage Note Payable [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other Secured Notes Payable	12,343			12,454
Real Estate Credit Facility [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other Secured Notes Payable	10,806			11,733
Carrying Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Finance Receivables, net	1,532,810	[1]		1,370,800	[1]
Dealer Finance Receivables - GO, net	92,278			40,956
Portfolio Warehouse Facilities	78,000			57,200
Senior Secured Notes Payable	253,766			198,320
Carrying Value [Member] | Securitization Debt [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Portfolio Term Financings	720,967			677,118
Carrying Value [Member] | Portfolio Term Residual Financing [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Portfolio Term Financings	100,000			25,000
Carrying Value [Member] | Bank Term Financings [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Portfolio Term Financings	287,829			347,360
Carrying Value [Member] | Revolving Inventory Facility [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other Secured Notes Payable	111,321			91,320
Carrying Value [Member] | Mortgage Note Payable [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other Secured Notes Payable	12,343			12,454
Carrying Value [Member] | Real Estate Credit Facility [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other Secured Notes Payable	10,806			11,733
Fair Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Finance Receivables, net	1,624,120	[1]		1,441,026	[1]
Dealer Finance Receivables - GO, net	96,615			40,956
Portfolio Warehouse Facilities	78,000			57,200
Senior Secured Notes Payable	274,067			220,135
Fair Value [Member] | Securitization Debt [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Portfolio Term Financings	729,689			702,031
Fair Value [Member] | Portfolio Term Residual Financing [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Portfolio Term Financings	112,961			25,000
Fair Value [Member] | Bank Term Financings [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Portfolio Term Financings	287,829			347,360
Fair Value [Member] | Revolving Inventory Facility [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other Secured Notes Payable	110,171			91,600
Fair Value [Member] | Mortgage Note Payable [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other Secured Notes Payable	11,100			11,200
Fair Value [Member] | Real Estate Credit Facility [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other Secured Notes Payable	$ 10,776			$ 11,700

[1] Represents finance receivable principal balances, plus accrued interest, less the allowance for credit losses.