Consolidated Income Statements (USD $) In Millions, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Revenue:
TOTAL REVENUE	$ 15,668.8	$ 13,832.3	$ 12,461.0
Cost of Sales:
TOTAL COST OF SALES	13,182.4	11,528.3	10,333.5
Gross Profit:
TOTAL GROSS PROFIT	2,486.4	2,304.0	2,127.5
Selling, general & administrative expenses	1,749.5	1,649.4	1,552.1
Depreciation and amortization	87.3	83.7	76.8
Franchise rights impairment	4.2	0	0
Other expenses (income), net	0.1	(1.1)	2.0
OPERATING INCOME	645.3	572.0	496.6
Non-operating income (expense) items:
Floorplan interest expense	(45.5)	(42.7)	(42.5)
Other interest expense	(86.9)	(66.0)	(56.1)
Loss on debt extinguishment	0	(2.2)	(19.6)
Interest income	0.3	0.7	1.4
Other income (losses), net	3.6	(0.5)	1.5
INCOME FROM CONTINUING OPERATIONS BEFORE INCOME TAXES	516.8	461.3	381.3
Income tax provision	199.5	177.1	146.0
NET INCOME FROM CONTINUING OPERATIONS	317.3	284.2	235.3
Loss from discontinued operations, net of income taxes	(0.9)	(2.8)	(8.7)
NET INCOME	316.4	281.4	226.6
BASIC EARNINGS (LOSS) PER SHARE:
Continuing operations	$ 2.56	$ 1.96	$ 1.50
Discontinued operations	$ (0.01)	$ (0.02)	$ (0.06)
Net income	$ 2.56	$ 1.94	$ 1.44
Weighted average common shares outstanding	123.8	144.8	156.9
DILUTED EARNINGS (LOSS) PER SHARE:
Continuing operations	$ 2.52	$ 1.93	$ 1.48
Discontinued operations	$ (0.01)	$ (0.02)	$ (0.05)
Net income	$ 2.52	$ 1.91	$ 1.43
Weighted average common shares outstanding	125.8	147.3	158.6
COMMON SHARES OUTSTANDING, net of treasury stock	120.9	135.8	148.4
New Vehicle [Member]
Revenue:
TOTAL REVENUE	8,906.9	7,498.9	6,669.1
Cost of Sales:
TOTAL COST OF SALES	8,327.4	6,951.2	6,217.9
Gross Profit:
TOTAL GROSS PROFIT	579.5	547.7	451.2
Used Vehicle [Member]
Revenue:
TOTAL REVENUE	3,714.7	3,512.8	3,116.1
Cost of Sales:
TOTAL COST OF SALES	3,415.4	3,228.0	2,849.4
Gross Profit:
TOTAL GROSS PROFIT	299.3	284.8	266.7
Parts and Service [Member]
Revenue:
TOTAL REVENUE	2,399.2	2,293.1	2,209.1
Cost of Sales:
TOTAL COST OF SALES	1,391.3	1,323.0	1,245.9
Gross Profit:
TOTAL GROSS PROFIT	1,007.9	970.1	963.2
Finance and Insurance, Net [Member]
Revenue:
TOTAL REVENUE	571.2	474.5	418.9
Gross Profit:
TOTAL GROSS PROFIT	571.2	474.5	418.9
Other Goods and Services [Member]
Revenue:
TOTAL REVENUE	76.8	53.0	47.8
Cost of Sales:
TOTAL COST OF SALES	48.3	26.1	20.3
Gross Profit:
TOTAL GROSS PROFIT	$ 28.5	$ 26.9	$ 27.5