Segment Information - Summary of Reportable Operating Segment (Details)	12 Months Ended
	Dec. 31, 2022 USD ($) Segment	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Segment Reporting Information [Line Items]
Operating income (loss)	$ 314,000,000.0	$ 538,400,000	$ 33,900,000
Interest expense, other, net	(89,900,000)	(48,000,000.0)	(41,600,000)
Other income (expense), net	200,000	(15,500,000)	100,000
Income (loss) from continuing operations before taxes	190,000,000.0	458,200,000	(34,800,000)
Segment Schedule Footnotes
Asset impairment charges	320,400,000	100,000	270,000,000.0
Nonrecurring Compensation Expense		6,500,000
Total floor plan interest expense	34,300,000	16,700,000	27,200,000
Depreciation, Depletion and Amortization, Nonproduction	127,500,000	101,100,000	91,000,000.0
Total assets	4,978,300,000	4,975,100,000
Cash and cash equivalents	229,200,000	299,400,000	170,300,000	$ 29,100,000
Goodwill	231,000,000.0	416,400,000	214,000,000.0
Intangible Assets, Net (Excluding Goodwill)	396,700,000	480,200,000
Other corporate assets	$ 0	200,000
Number of operating segments | Segment	3
Segment Income	$ 510,400,000	458,300,000	235,200,000
EchoPark Segment Income	(133,900,000)	(72,000,000.0)	4,000,000.0
Powersports Segment Segment Income	2,700,000	0	0
Segment Retail Units Sold
Franchised Dealerships Used Vehicle Revenue	3,391,500,000	2,901,000,000	2,345,900,000
Franchised Dealerships Wholesale Revenue	314,000,000.0	257,200,000	168,700,000
Franchised Dealerships Fixed Ops Revenue	1,588,000,000	1,340,400,000	1,194,400,000
Franchised Dealerships F&I Revenue	510,100,000	443,500,000	357,800,000
Franchised Dealerships Segment Revenue	11,484,600,000	10,051,100,000	8,348,000,000
EchoPark New Vehicle Revenue	9,200,000	9,000,000.0	0
EchoPark Used Vehicle Revenue	2,116,800,000	2,032,600,000	1,258,200,000
EchoPark Wholesale Revenue	170,600,000	110,000,000.0	28,700,000
EchoPark F&I Revenue	166,400,000	193,700,000	132,100,000
EchoPark Segment Revenue	2,463,000,000	2,345,300,000	1,419,000,000
Powersports Used Vehicle Revenue	7,100,000	0	0
Powersports Wholesale Vehicle Revenue	300,000	0	0
Powersports Fixed Ops Revenue	11,700,000	0	0
Powersports F&I Revenue	2,600,000	0	0
Powersports Segment Revenues	53,500,000	0	0
Total revenues	14,001,100,000	12,396,400,000	9,767,000,000
EchoPark Segment Assets	267,600,000	740,600,000
PowerSport Segment Assets [Domain]	117,800,000	0
Powersport Interest Expense, Other, Net	1,000,000.0	0	0
Powersports Floorplan Exp	0	0	0
Powersports Depreciation and Amortization	1,000,000.0	0	0
Gain on EchoPark Disposal			5,200,000
Debt Extinguishment Costs		15,500,000
Business Combination, Acquisition Related Costs	600,000	3,000,000
Gain (Loss) on Disposition of Property Plant Equipment	9,100,000
Gain (loss) pre-tax loss on long-term compensation expense	4,400,000
Powersports Capital Expenditures	200,000	0	0
Fleet New Vehicles [Member]
Segment Retail Units Sold
Total revenues	99,400,000	124,600,000	56,800,000
Total new vehicles
Segment Retail Units Sold
Total revenues	5,722,000,000	5,118,000,000	4,281,200,000
Retail New Vehicles [Member]
Segment Retail Units Sold
Powersports New Vehicle Revenue	31,800,000	0	0
Total revenues	5,622,600,000	4,993,400,000	4,224,400,000
EchoPark Total Impairment [Member]
Segment Schedule Footnotes
Asset impairment charges	204,900,000	100,000
Franchised Dealership Impairment [Member]
Segment Schedule Footnotes
Asset impairment charges	115,500,000		270,000,000.0
FranchisedDealershipMember [Member] | Fleet New Vehicles [Member]
Segment Retail Units Sold
Total revenues	99,400,000	124,600,000	56,800,000
FranchisedDealershipMember [Member] | TotalNewVehicle
Segment Retail Units Sold
Total revenues	5,681,000,000	5,109,000,000	4,281,200,000
FranchisedDealershipMember [Member] | Retail New Vehicles [Member]
Segment Retail Units Sold
Total revenues	$ 5,581,600,000	4,984,400,000	4,224,400,000
Franchised Dealerships [Member]
Segment Schedule Footnotes
Asset impairment charges		$ 0
PreOwnedStoreMember [Member]
Segment Schedule Footnotes
Asset impairment charges			0
Operating segments | Income (loss) from continuing operations before taxes | Franchised Dealership Impairment [Member]
Segment Schedule Footnotes
Asset impairment charges			$ 100,000