CONSOLIDATED STATEMENTS OF INCOME - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
REVENUE:
New vehicle	$ 3,863.3	$ 3,788.7	$ 3,561.1
Used vehicle	2,131.6	1,972.4	1,834.1
Finance and insurance, net	316.0	292.3	275.2
TOTAL REVENUE	7,210.3	6,874.4	6,456.5
COST OF SALES:
New vehicle	3,703.8	3,623.5	3,392.1
Used vehicle	1,997.5	1,842.7	1,712.2
Cost of Goods and Services Sold	340.1	305.2	296.3
Parts and service	899.4	821.0	786.1
TOTAL COST OF SALES	6,041.4	5,771.4	5,400.6
GROSS PROFIT	1,168.9	1,103.0	1,055.9
OPERATING EXPENSES:
Selling, general, and administrative	799.8	755.8	729.7
Depreciation and amortization	36.2	33.7	32.1
Franchise rights impairment	7.1	3.7	5.1
Other operating expenses (income), net	0.8	(1.1)	1.3
INCOME FROM OPERATIONS	325.0	310.9	287.7
OTHER EXPENSES (INCOME):
Floor plan interest expense	37.9	32.5	22.7
Other interest expense, net	54.9	53.1	53.9
Swap interest expense	0.0	0.5	2.0
Gain on divestitures	(11.7)	0.0	0.0
Total other expenses, net	81.1	86.1	78.6
INCOME BEFORE INCOME TAXES	243.9	224.8	209.1
Income tax expense	59.5	56.8	70.0
NET INCOME	$ 184.4	$ 168.0	$ 139.1
Basic—
Net income (in dollars per share)	$ 9.65	$ 8.36	$ 6.69
Diluted—
Net income (in dollars per share)	$ 9.55	$ 8.28	$ 6.62
WEIGHTED AVERAGE COMMON SHARES OUTSTANDING:
Basic (in shares)	19.1	20.1	20.8
Restricted stock (in shares)	0.1	0.1	0.1
Performance share units (in shares)	0.1	0.1	0.1
Diluted (in shares)	19.3	20.3	21.0