Debt Obligations Other Secured Notes Payable (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012	Mar. 31, 2013 Revolving Inventory Facility [Member]		Dec. 31, 2012 Revolving Inventory Facility [Member]		Mar. 31, 2013 Mortgage Note Payable [Member]		Dec. 31, 2012 Mortgage Note Payable [Member]		Mar. 31, 2013 Real Estate Credit Facility [Member]		Dec. 31, 2012 Real Estate Credit Facility [Member]		Mar. 31, 2013 Equipment Note Payable [Member]		Dec. 31, 2012 Equipment Note Payable [Member]		Mar. 31, 2013 LIBOR [Member] Revolving Inventory Facility [Member]	Mar. 31, 2013 LIBOR [Member] Real Estate Credit Facility [Member]	Mar. 31, 2013 Prime Rate [Member] Equipment Note Payable [Member]	Dec. 31, 2012 Seasonal Increase [Member] Revolving Inventory Facility [Member]	Apr. 30, 2013 Subsequent Event [Member] Prime Rate [Member] Equipment Note Payable [Member]
Debt Instrument [Line Items]
Balance	$ 136,668	$ 117,281	$ 111,321		$ 91,320		$ 12,397		$ 12,454		$ 11,269		$ 11,733		$ 1,681		$ 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]	4.20%	[3]	4.21%	[3]	4.75%	[3]	4.75%	[3]
Total Other Secured Notes Payable	$ 155,000	$ 165,000
Basis spread on variable interest rate																			3.50%	4.00%	1.50%		1.00%

[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.