CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Operating Activities:
Net income	$ 923.4	$ 1,058.6	$ 1,386.2
Adjustments to reconcile net income to net cash from operating activities:
Depreciation	158.0	141.0	127.3
Earnings of equity method investments, net of distributions	(127.9)	(174.6)	(183.3)
Deferred income taxes	(13.0)	101.8	124.2
Stock-based compensation	29.4	28.1	26.7
Goodwill impairment charges	0.0	40.7	0.0
Changes in operating assets and liabilities:
Accounts receivable	125.4	(194.7)	(192.9)
Inventories	(196.7)	(666.2)	(444.4)
Other current assets	(43.8)	(29.5)	(36.2)
Floor plan notes payable	316.1	659.7	487.1
Accounts payable and accrued expenses	42.9	(13.0)	81.7
Other	(34.0)	141.7	82.6
Net cash provided by operating activities	1,179.8	1,093.6	1,459.0
Investing Activities:
Purchases of property, equipment, and improvements	(368.7)	(375.3)	(282.5)
Proceeds from sale of dealerships	82.1	0.0	13.1
Proceeds from sale of property and equipment	26.2	30.7	32.3
Proceeds from sale of equity method investment	20.7	0.0	0.0
Acquisitions net, including repayment of sellers' floor plan notes payable of $212.5, $24.3, and $51.3, respectively	(786.2)	(214.9)	(393.4)
Other	(11.1)	(12.8)	(11.2)
Net cash used in investing activities	(1,037.0)	(572.3)	(641.7)
Financing Activities:
Proceeds from borrowings under revolving U.S. credit agreement and mortgage facilities	4,301.4	3,150.3	2,101.0
Repayments under revolving U.S. credit agreement and mortgage facilities	(4,182.7)	(3,227.8)	(2,101.0)
Net cash borrowings of other debt	113.3	73.2	160.1
Net (repayments) borrowings of floor plan notes payable — non-trade	(15.4)	46.5	82.9
Repurchases of common stock	(58.7)	(358.7)	(869.3)
Payments of tax withholding for stock-based compensation	(18.8)	(23.5)	(17.2)
Dividends	(274.4)	(189.1)	(154.1)
Payment of debt issuance costs	(1.0)	(2.1)	(0.3)
Purchase of subsidiary shares from non-controlling interest	(16.7)	0.0	0.0
Other	(11.7)	0.1	(0.1)
Net cash used in financing activities	(164.7)	(531.1)	(798.0)
Effect of exchange rate changes on cash and cash equivalents	(2.1)	(0.3)	(13.5)
Net change in cash and cash equivalents	(24.0)	(10.1)	5.8
Cash and cash equivalents, beginning of period	96.4	106.5	100.7
Cash and cash equivalents, end of period	72.4	96.4	106.5
Cash paid for:
Interest	271.6	214.3	112.8
Income taxes	317.4	288.1	343.4
Non-cash activities:
Receivable From Sale Of Investment	$ 10.4	$ 0.0	$ 0.0