Debt Obligations - Other Secured Notes Payable (Details) (USD $) In Thousands, unless otherwise specified																			9 Months Ended
	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2013 Revolving Inventory Facility [Member]		Dec. 31, 2012 Revolving Inventory Facility [Member]		Sep. 30, 2013 Mortgage Note Payable [Member]		Dec. 31, 2012 Mortgage Note Payable [Member]		Sep. 30, 2013 Real Estate Credit Facility [Member] property		Dec. 31, 2012 Real Estate Credit Facility [Member]		Sep. 30, 2013 Equipment Note Payable [Member]		Dec. 31, 2012 Equipment Note Payable [Member]		Sep. 30, 2013 One Month LIBOR [Member] Revolving Inventory Facility [Member]	Sep. 30, 2013 LIBOR [Member] Real Estate Credit Facility [Member]	Sep. 30, 2013 LIBOR [Member] Real Estate Credit Facility [Member] Properties Added to the Facility Subsequent to August 22, 2013 [Member]	Sep. 30, 2013 Prime Rate [Member] Equipment Note Payable [Member]	Dec. 31, 2012 Seasonal Increase [Member] Revolving Inventory Facility [Member]
Debt Instrument [Line Items]
Balance	$ 148,965	$ 117,281	$ 121,321		$ 91,320		$ 12,288		$ 12,454		$ 14,014		$ 11,733		$ 1,342		$ 1,774						$ 10,000
Max Facility Capacity	425,000	425,000	130,000		140,000	[1]					25,000		25,000
Stated Advance Rate			85.00%	[2]	85.00%	[2]					70.00%		70.00%
Interest Rate			3.75%	[3]	3.75%	[3]	5.87%	[3]	5.87%	[3]	4.05%	[3]	4.21%	[3]	4.25%	[3]	4.75%	[3]
Total Other Secured Notes Payable	$ 155,000	$ 165,000
Basis spread on variable interest rate																			3.50%	4.00%	3.50%	1.00%
Properties used as a collateral											11

[1] Inclusive of a $10.0 million seasonal increase in the months of November through the end of January.

[2] Advance rate is based on qualifying vehicle cost and is secured by our entire vehicle inventory.

[3] Interest rate at period end equal to contractual benchmark plus index