Consolidated Statements of Operations (Unaudited) - USD ($) shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Revenues:
Total revenues	$ 3,620.2	$ 3,332.4	$ 9,182.5	$ 9,403.8
Cost of sales:
Total cost of sales	2,968.6	2,821.5	7,605.6	7,948.6
Gross profit	651.6	510.9	1,576.9	1,455.2
Asset impairments	0.0	0.0	7.9	0.5
Selling, general and administrative	389.1	343.2	1,039.6	1,021.5
Depreciation and amortization	22.9	20.9	67.3	60.9
Operating income	239.6	146.8	462.1	372.3
Floor plan interest expense	(6.1)	(17.9)	(28.3)	(55.5)
Other interest expense, net	(16.6)	(14.8)	(50.4)	(45.0)
Other income, net	2.2	3.3	8.2	8.9
Income before income taxes	219.1	117.4	391.6	280.7
Income tax provision	(60.3)	(32.2)	(108.9)	(77.2)
Net income	$ 158.8	$ 85.2	$ 282.7	$ 203.5
Basic net income per share (in dollars per share)	$ 6.95	$ 3.67	$ 12.30	$ 8.77
Shares used in basic per share calculations (in shares)	22.9	23.2	23.0	23.2
Diluted net income per share (in dollars per share)	$ 6.86	$ 3.64	$ 12.18	$ 8.72
Shares used in diluted per share calculations (in shares)	23.1	23.4	23.2	23.3
Cash dividends paid per Class A and Class B share (in dollars per share)	$ 0.31	$ 0.30	$ 0.91	$ 0.89
New vehicle retail
Revenues:
Total revenues	$ 1,883.3	$ 1,824.8	$ 4,624.6	$ 4,993.3
Cost of sales:
Total cost of sales	1,743.2	1,724.8	4,314.2	4,711.9
Used vehicle retail
Revenues:
Total revenues	1,093.2	916.3	2,889.7	2,632.4
Cost of sales:
Total cost of sales	948.4	816.6	2,556.8	2,355.0
Used vehicle wholesale
Revenues:
Total revenues	98.8	74.4	216.8	233.5
Cost of sales:
Total cost of sales	91.2	73.3	206.5	229.7
Finance and insurance
Revenues:
Total revenues	160.5	136.3	407.2	382.7
Service, body and parts
Revenues:
Total revenues	359.5	340.5	964.9	993.3
Cost of sales:
Total cost of sales	163.6	169.0	456.5	492.2
Fleet and other
Revenues:
Total revenues	24.9	40.1	79.3	168.6
Cost of sales:
Total cost of sales	$ 22.2	$ 37.8	$ 71.6	$ 159.8