| Segment Information (Tables) - USD ($) | 12 Months Ended | ||
|---|---|---|---|
| Dec. 31, 2021 | Dec. 31, 2020 | Dec. 31, 2019 | |
| Segment Reporting Information [Line Items] | |||
| Total capital expenditures | $ 298,200,000 | $ 127,200,000 | $ 125,600,000 | 
| EchoPark Capital Expenditures | 93,600,000 | 34,900,000 | 36,300,000 | 
| Franchised Dealerships Capital Expenditures | 204,600,000 | 92,300,000 | 89,300,000 | 
| EchoPark Interest Expense, Other, Net | 1,700,000 | 900,000 | 1,800,000 | 
| Franchised Segment Interest Expense, Other, Net | 46,300,000 | 40,700,000 | 51,200,000 | 
| Gain on EchoPark Disposal | 5,200,000 | ||
| Gain on Franchise Disposal | 1,800,000 | 4,000,000 | 76,000,000 | 
| Debt Extinguishment Costs | 15,500,000 | 7,200,000 | |
| Executive transition costs | 6,300,000 | ||
| EchoPark Segment Assets | 740,600,000 | 478,900,000 | |
| Franchised Dealerships Segment Assets | 3,934,900,000 | 3,096,800,000 | |
| EchoPark Depreciation and Amortization | 16,300,000 | 11,100,000 | 10,500,000 | 
| Franchised Dealerships Depreciation and Amortization | 84,800,000 | 79,900,000 | 82,600,000 | 
| EchoPark Floorplan Exp | 4,900,000 | 3,200,000 | 3,500,000 | 
| Franchised Dealerships Floorplan Exp | 11,800,000 | 24,000,000.0 | 45,000,000.0 | 
| Segment Income | 458,300,000 | 235,200,000 | 220,400,000 | 
| EchoPark Segment Income | (72,000,000.0) | 4,000,000.0 | 9,100,000 | 
| Franchised Dealerships Segment Income | 530,300,000 | 231,200,000 | 211,300,000 | 
| EchoPark Segment Revenue | 2,345,300,000 | 1,419,000,000 | 1,162,000,000 | 
| EchoPark F&I Revenue | 193,700,000 | 132,100,000 | 113,800,000 | 
| EchoPark Wholesale Revenue | 110,000,000.0 | 28,700,000 | 22,900,000 | 
| EchoPark Used Vehicle Revenue | 2,032,600,000 | 1,258,200,000 | 1,025,300,000 | 
| Franchised Dealerships Segment Revenue | 10,051,100,000 | 8,348,000,000 | 9,292,300,000 | 
| Franchised Dealerships F&I Revenue | 443,500,000 | 357,800,000 | 363,100,000 | 
| Franchised Dealerships Fixed Ops Revenue | 1,340,400,000 | 1,194,400,000 | 1,366,500,000 | 
| Franchised Dealerships New Vehicle Revenue | 5,109,000,000 | 4,281,200,000 | 4,889,200,000 | 
| Franchised Dealerships Used Vehicle Revenue | 2,901,000,000 | 2,345,900,000 | 2,493,500,000 | 
| Franchised Dealerships Wholesale Revenue | $ 257,200,000 | $ 168,700,000 | $ 180,000,000.0 | 
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- Definition Debt Extinguishment Costs No definition available. 
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- Definition EchoPark Capital Expenditures No definition available. 
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- Definition EchoPark Depreciation and Amortization No definition available. 
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- Definition EchoPark F&I Revenue No definition available. 
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- Definition EchoPark Floorplan Exp No definition available. 
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- Definition EchoPark Interest Expense, Other, Net No definition available. 
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- Definition EchoPark Segment Assets No definition available. 
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- Definition EchoPark Segment Income No definition available. 
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- Definition EchoPark Segment Revenue No definition available. 
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- Definition EchoPark Used Vehicle Revenue No definition available. 
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- Definition EchoPark Wholesale Revenue No definition available. 
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- Definition Executive Transition Costs No definition available. 
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- Definition Franchised Dealerships Capital Expenditures No definition available. 
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- Definition Franchised Dealerships Depreciation and Amortization No definition available. 
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- Definition Franchised Dealerships F&I Revenue No definition available. 
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- Definition Franchised Dealerships Fixed Ops Revenue No definition available. 
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- Definition Franchised Dealerships Floorplan Exp No definition available. 
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- Definition Franchised Dealerships New Vehicle Revenue No definition available. 
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- Definition Franchised Dealerships Segment Assets No definition available. 
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- Definition Franchised Dealerships Segment Income No definition available. 
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- Definition Franchised Dealerships Segment Revenue No definition available. 
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- Definition Franchised Dealerships Used Vehicle Revenue No definition available. 
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- Definition Franchised Dealerships Wholesale Revenue No definition available. 
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- Definition Franchised Segment Interest Expense, Other, Net No definition available. 
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- Definition Gain on EchoPark Disposal No definition available. 
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- Definition Gain on Franchise Disposal No definition available. 
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- Definition Segment Income No definition available. 
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- Definition The cash outflow associated with the acquisition of long-lived, physical assets that are used in the normal conduct of business to produce goods and services and not intended for resale; includes cash outflows to pay for construction of self-constructed assets. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef 
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. No definition available. 
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