Unaudited Condensed Consolidated Balance Sheets (USD $) In Millions, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
ASSETS
Cash and cash equivalents	$ 69.7	$ 69.7
Receivables, net	621.4	698.4
Inventory	2,625.2	2,396.9
Other current assets	190.2	196.1
Total Current Assets	3,506.5	3,361.1
PROPERTY AND EQUIPMENT, net of accumulated depreciation of $870.0 million and $826.8 million, respectively	2,122.9	2,095.1
GOODWILL	1,253.0	1,237.4
OTHER INTANGIBLE ASSETS, NET	328.2	291.3
OTHER ASSETS	242.4	218.1
Total Assets	7,453.0	7,203.0
LIABILITIES AND SHAREHOLDERS' EQUITY
Vehicle floorplan payable	2,748.1	2,540.2
Accounts payable	225.7	217.2
Current maturities of long-term debt	29.6	29.8
Other current liabilities	396.5	414.5
Total Current Liabilities	3,399.9	3,201.7
LONG-TERM DEBT, NET OF CURRENT MATURITIES	1,907.2	2,066.3
DEFERRED INCOME TAXES	97.2	89.4
OTHER LIABILITIES	166.2	157.1
COMMITMENTS AND CONTINGENCIES (Note 10)
SHAREHOLDERS' EQUITY:
Preferred stock, par value $0.01 per share; 5,000,000 shares authorized; none issued	0	0
Common stock, par value $0.01 per share; 1,500,000,000 shares authorized; 163,562,149 shares issued at June 30, 2013, and December 31, 2012, including shares held in treasury	1.6	1.6
Additional paid-in capital	34.9	26.6
Retained earnings	3,135.9	2,963.0
Treasury stock, at cost; 42,227,239 and 42,705,580 shares held, respectively	(1,289.9)	(1,302.7)
Total Shareholders' Equity	1,882.5	1,688.5
Total Liabilities and Shareholders' Equity	7,453.0	7,203.0
Trade [Member]
LIABILITIES AND SHAREHOLDERS' EQUITY
Vehicle floorplan payable	1,944.0	1,766.3
Non-Trade [Member]
LIABILITIES AND SHAREHOLDERS' EQUITY
Vehicle floorplan payable	$ 804.1	$ 773.9