CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income (loss)	$ 88,500,000	$ 348,900,000	$ (51,400,000)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation and amortization of property and equipment	113,900,000	93,800,000	87,600,000
Debt issuance cost amortization	5,200,000	3,300,000	2,900,000
Stock-based compensation expense	20,500,000	15,000,000.0	11,700,000
Deferred income taxes	(12,700,000)	12,300,000	(33,700,000)
Asset impairment charges	320,400,000	100,000	270,000,000.0
Increase (Decrease) in Other Current Assets	(9,300,000)	12,400,000	(6,400,000)
Changes in assets and liabilities that relate to operations:
Receivables	(50,400,000)	500,000	64,800,000
Inventories	81,400,000	252,400,000	278,100,000
Other assets	(140,700,000)	55,700,000	(11,400,000)
Notes payable - floor plan - trade	25,100,000	(495,400,000)	(275,600,000)
Trade accounts payable and other liabilities	(35,800,000)	7,300,000	(55,500,000)
Total adjustments	317,600,000	(42,600,000)	332,500,000
Net cash provided by operating activities	406,100,000	306,300,000	281,100,000
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchase of businesses, net of cash acquired	(102,300,000)	(1,018,900,000)	(19,700,000)
Purchases of land, property and equipment	(227,100,000)	(298,200,000)	(127,200,000)
Proceeds from sales of property and equipment	29,700,000	13,100,000	37,100,000
Proceeds from sales of dealerships	0	6,600,000	9,600,000
Net cash used in investing activities	(299,700,000)	(1,297,400,000)	(100,200,000)
CASH FLOWS FROM FINANCING ACTIVITIES:
Net (repayments) borrowings on notes payable - floor plan - non-trade	(65,900,000)	439,600,000	60,800,000
Borrowings on revolving credit facilities	0	4,900,000	460,900,000
Repayments on revolving credit facilities	0	(4,900,000)	(460,900,000)
Proceeds from issuance of long-term debt	327,000,000.0	1,166,500,000	57,900,000
Debt issuance costs	(8,100,000)	(23,100,000)	(2,700,000)
Principal payments of long-term debt	(133,500,000)	(58,300,000)	(44,900,000)
Repurchase of debt securities	0	(262,900,000)	0
Purchases of treasury stock	(261,900,000)	(93,300,000)	(71,700,000)
Issuance of shares under stock compensation plans	8,700,000	7,700,000	(100,000)
Dividends paid	(34,500,000)	(18,300,000)	(17,100,000)
Net cash provided by (used in) financing activities	(176,600,000)	1,120,200,000	(39,700,000)
Reduction of Finance Lease Liabilities	(8,400,000)	(37,700,000)	(21,900,000)
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS	(70,200,000)	129,100,000	141,200,000
CASH AND CASH EQUIVALENTS, BEGINNING OF YEAR	299,400,000	170,300,000	29,100,000
CASH AND CASH EQUIVALENTS, END OF YEAR	229,200,000	299,400,000	170,300,000
SUPPLEMENTAL SCHEDULE OF NON-CASH FINANCING ACTIVITIES:
Change in fair value of interest rate swap and rate cap agreements (net of tax expense of $460, $2,351 and $2,178 in the years ended December 31, 2018, 2017 and 2016, respectively)	(400,000)	1,000,000.0	(200,000)
Cash paid (received) during the period for:
Income taxes	126,300,000	98,800,000	56,800,000
Interest, including amount capitalized	$ 116,900,000	$ 57,400,000	$ 69,300,000