Inventory Financing Agreements (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Inventory Financing Agreements [Line Items]
Accounts Payable Inventory Financing	$ 332.1	$ 256.6
Accounts Payable, Inventory Financing [Member]
Inventory Financing Agreements [Line Items]
Revolving Loan financing agreement	330.1	256.1
Other inventory financing agreements	2.0	0.5
Accounts Payable Inventory Financing	332.1	256.6
Previous Revolving Credit Facility [Member] | Accounts Payable, Inventory Financing [Member]
Inventory Financing Agreements [Line Items]
Floorplan sub-facility	$ 400.0