Description of Business and Summary of Significant Accounting Policies (Organization and Business, Inventory) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012 franchises stores	Dec. 31, 2011
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Owned And Operated New Vehicle Franchises	265
Number of stores	221
Number of Brands	32
Percentage of New Vehicle Sales Core Brand Vehicles	95.00%
Floorplan interest assistance, inventory cost reduction	$ 15.8	$ 11.8