Inventory Financing Agreements (Details) (USD $)	Mar. 31, 2013	Dec. 31, 2012
Inventory Financing Agreements [Line Items]
Accounts payable-inventory financing	$ 252,900,000	$ 249,200,000
Accounts Payable, Inventory Financing [Member]
Inventory Financing Agreements [Line Items]
Revolving Loan inventory financing agreement	252,800,000	248,300,000
Other inventory financing agreements	100,000	900,000
Accounts payable-inventory financing	252,900,000	249,200,000
Floorplan sub-facility	400,000,000
Other inventory financing agreements, current	$ 100,000	$ 900,000