CONDENSED CONSOLIDATED STATEMENTS OF INCOME - USD ($) shares in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
REVENUE:
New vehicle	$ 1,151,700,000	$ 822,100,000
Used vehicle	690,900,000	493,200,000
Parts and service	262,000,000.0	221,600,000
Finance and insurance, net	88,300,000	70,400,000
TOTAL REVENUE	2,192,900,000	1,607,300,000
COST OF SALES:
New vehicle	1,076,200,000	785,700,000
Used vehicle	635,100,000	462,500,000
Parts and service	98,900,000	86,700,000
TOTAL COST OF SALES	1,810,200,000	1,334,900,000
GROSS PROFIT	382,700,000	272,400,000
OPERATING EXPENSES:
Selling, general, and administrative	239,800,000	194,700,000
Depreciation and amortization	9,800,000	9,500,000
Franchise rights impairment	0	23,000,000.0
Other operating (income) expense, net	(3,200,000)	10,200,000
INCOME FROM OPERATIONS	136,300,000	35,000,000.0
OTHER EXPENSES (INCOME):
Floor plan interest expense	2,900,000	7,000,000.0
Other interest expense, net	14,000,000.0	17,000,000.0
Loss on extinguishment of long-term debt, net	0	20,600,000
Gain on dealership divestitures, net	0	(33,700,000)
Total other expense, net	16,900,000	10,900,000
INCOME BEFORE INCOME TAXES	119,400,000	24,100,000
Income tax expense	26,600,000	4,600,000
NET INCOME	$ 92,800,000	$ 19,500,000
Basic—
Net income (in dollars per share)	$ 4.81	$ 1.02
Diluted—
Net income (in dollars per share)	$ 4.78	$ 1.01
WEIGHTED AVERAGE SHARES OUTSTANDING:
Basic (in shares)	19.3	19.1
Restricted stock (in shares)	0.1	0.1
Performance share units (in shares)	0.0	0.1
Diluted (in shares)	19.4	19.3