Unaudited Condensed Consolidated Balance Sheets - USD ($)	Sep. 30, 2020	Dec. 31, 2019
ASSETS
Cash and cash equivalents	$ 350,500,000	$ 42,000,000.0
Receivables, net	682,500,000	916,700,000
Inventory	2,482,500,000	3,305,800,000
Other current assets	139,400,000	146,600,000
Total Current Assets	3,654,900,000	4,411,100,000
PROPERTY AND EQUIPMENT, net of accumulated depreciation of $1.6 billion and $1.5 billion, respectively	3,125,100,000	3,174,600,000
OPERATING LEASE ASSETS	329,000,000.0	333,100,000
GOODWILL	1,186,500,000	1,501,900,000
OTHER INTANGIBLE ASSETS, NET	521,800,000	581,600,000
OTHER ASSETS	752,000,000.0	541,000,000.0
Total Assets	9,569,300,000	10,543,300,000
LIABILITIES AND SHAREHOLDERS’ EQUITY
Vehicle floorplan payable	2,308,600,000	3,575,800,000
Accounts payable	344,500,000	290,300,000
Commercial paper	0	170,000,000.0
Current maturities of long-term debt	307,700,000	355,600,000
Accrued payroll and benefits	214,300,000	178,400,000
Other current liabilities	535,500,000	530,100,000
Total Current Liabilities	3,710,600,000	5,100,200,000
LONG-TERM DEBT, NET OF CURRENT MATURITIES	1,782,000,000.0	1,578,500,000
NONCURRENT OPERATING LEASE LIABILITIES	304,700,000	305,000,000.0
DEFERRED INCOME TAXES	110,100,000	135,100,000
OTHER LIABILITIES	304,000,000.0	262,400,000
COMMITMENTS AND CONTINGENCIES (Note 12)
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; 102,562,149 shares issued at September 30, 2020, and December 31, 2019, including shares held in treasury	1,000,000.0	1,000,000.0
Additional paid-in capital	41,300,000	35,900,000
Retained earnings	3,917,900,000	3,688,300,000
Treasury stock, at cost; 14,717,090 and 13,212,974 shares held, respectively	(602,300,000)	(563,100,000)
Total Shareholders’ Equity	3,357,900,000	3,162,100,000
Total Liabilities and Shareholders’ Equity	9,569,300,000	10,543,300,000
PROPERTY AND EQUIPMENT, accumulated depreciation	$ 1,600,000,000	$ 1,500,000,000
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock authorized (in shares)	5,000,000	5,000,000
Preferred stock issued (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock authorized (in shares)	1,500,000,000	1,500,000,000
Common stock issued (in shares)	102,562,149	102,562,149
Treasury stock (in shares)	14,717,090	13,212,974
Trade [Member]
LIABILITIES AND SHAREHOLDERS’ EQUITY
Vehicle floorplan payable	$ 1,467,600,000	$ 2,120,600,000
Non-Trade [Member]
LIABILITIES AND SHAREHOLDERS’ EQUITY
Vehicle floorplan payable	$ 841,000,000.0	$ 1,455,200,000