CONSOLIDATED STATEMENTS OF INCOME - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
REVENUE:
New vehicle	$ 3,652.5	$ 3,230.6	$ 2,952.2
Used vehicle	1,931.7	1,741.5	1,564.2
Parts and service	740.7	666.6	611.6
Finance and insurance, net	263.4	229.0	206.9
TOTAL REVENUE	6,588.3	5,867.7	5,334.9
COST OF SALES:
New vehicle	3,449.5	3,032.3	2,770.9
Used vehicle	1,799.9	1,613.8	1,444.1
Parts and service	278.1	254.4	243.9
TOTAL COST OF SALES	5,527.5	4,900.5	4,458.9
GROSS PROFIT	1,060.8	967.2	876.0
OPERATING EXPENSES:
Selling, general, and administrative	729.9	671.6	617.8
Depreciation and amortization	29.5	26.4	24.3
Other operating (income) expense, net	(0.2)	1.0	7.8
INCOME FROM OPERATIONS	301.6	268.2	226.1
OTHER (INCOME) EXPENSES:
Floor plan interest expense	16.1	12.4	12.5
Other interest expense, net	44.0	38.9	39.0
Swap interest expense	3.0	2.0	2.5
Loss on extinguishment of long-term debt, net	0.0	31.9	6.8
Gain on divestitures	(34.9)	0.0	0.0
Total other expenses, net	28.2	85.2	60.8
INCOME FROM CONTINUING OPERATIONS BEFORE INCOME TAXES	273.4	183.0	165.3
Income tax expense	104.0	71.0	64.2
INCOME FROM CONTINUING OPERATIONS	169.4	112.0	101.1
Discontinued operations, net of tax	(0.2)	(0.4)	8.0
NET INCOME	$ 169.2	$ 111.6	$ 109.1
Basic—
Continuing operations (in dollars per share)	$ 6.44	$ 3.75	$ 3.29
Discontinued operations (in dollars per share)	(0.01)	(0.02)	0.26
Net income (in dollars per share)	6.43	3.73	3.55
Diluted—
Continuing operations (in dollars per share)	6.42	3.72	3.25
Discontinued operations (in dollars per share)	(0.01)	(0.01)	0.26
Net income (in dollars per share)	$ 6.41	$ 3.71	$ 3.51
WEIGHTED AVERAGE COMMON SHARES OUTSTANDING:
Basic (in shares)	26.3	29.9	30.7
Restricted stock (in shares)	0.0	0.1	0.2
Performance share units (in shares)	0.1	0.1	0.2
Diluted (in shares)	26.4	30.1	31.1