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Financial Instruments and Fair Value Measurements (Narrative) (Details)	3 Months Ended			12 Months Ended
	Mar. 31, 2021 store	Jun. 30, 2020 USD ($)	Mar. 31, 2020 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Goodwill impairment				$ 0	$ 318,300,000	$ 0
Franchise rights impairment				0	57,500,000	9,600,000
Franchise rights impairment, number of stores | store	8
Reporting Unit, Premium Luxury [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Goodwill impairment					257,400,000
Reporting Unit, Collision Centers [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Goodwill impairment					41,600,000
Reporting Unit, Parts Centers [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Goodwill impairment					19,300,000
Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Goodwill impairment			$ 318,300,000	0	318,300,000
Nonrecurring [Member] | Reporting Unit, Premium Luxury [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Goodwill impairment			257,400,000
Nonrecurring [Member] | Reporting Unit, Collision Centers [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Goodwill impairment			41,600,000
Nonrecurring [Member] | Reporting Unit, Parts Centers [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Goodwill impairment			19,300,000
Nonrecurring [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value Measurement Inputs and Valuation Techniques [Abstract]
Franchise rights				0	26,200,000
Nonrecurring [Member] | Other Intangible Assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impairment of finite lived intangible assets					2,400,000
Franchise Rights [Member] | Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Franchise rights impairment		$ 0	57,500,000	0		$ 9,600,000
Franchise Rights [Member] | Nonrecurring [Member] | Fair Value, Inputs, Level 3 [Member] | Valuation Technique, Discounted Cash Flow [Member]
Fair Value Measurement Inputs and Valuation Techniques [Abstract]
Franchise rights			$ 24,600,000
Franchise Rights [Member] | Nonrecurring [Member] | Fair Value, Inputs, Level 3 [Member] | Measurement Input, Long-term Revenue Growth Rate [Member] | Valuation Technique, Discounted Cash Flow [Member]
Fair Value Measurement Inputs and Valuation Techniques [Abstract]
Franchise Rights, Measurement Input			0.020
Franchise Rights [Member] | Nonrecurring [Member] | Arithmetic Average [Member] | Fair Value, Inputs, Level 3 [Member] | Measurement Input, Weighted Average Cost of Capital [Member] | Valuation Technique, Discounted Cash Flow [Member]
Fair Value Measurement Inputs and Valuation Techniques [Abstract]
Franchise Rights, Measurement Input			0.085
Franchise Rights [Member] | Nonrecurring [Member] | Arithmetic Average [Member] | Fair Value, Inputs, Level 3 [Member] | Measurement Input, Discount Rate [Member] | Valuation Technique, Discounted Cash Flow [Member]
Fair Value Measurement Inputs and Valuation Techniques [Abstract]
Franchise Rights, Measurement Input			0.121
Franchise Rights [Member] | Nonrecurring [Member] | Arithmetic Average [Member] | Fair Value, Inputs, Level 3 [Member] | Measurement Input, Long-term Pretax Income Margin [Member] | Valuation Technique, Discounted Cash Flow [Member]
Fair Value Measurement Inputs and Valuation Techniques [Abstract]
Franchise Rights, Measurement Input			0.014
Franchise Rights [Member] | Nonrecurring [Member] | Arithmetic Average [Member] | Fair Value, Inputs, Level 3 [Member] | Measurement Input, Contributory Asset Charges [Member] | Valuation Technique, Discounted Cash Flow [Member]
Fair Value Measurement Inputs and Valuation Techniques [Abstract]
Franchise Rights, Measurement Input			0.062
Franchise Rights [Member] | Nonrecurring [Member] | Minimum [Member] | Fair Value, Inputs, Level 3 [Member] | Measurement Input, Discount Rate [Member] | Valuation Technique, Discounted Cash Flow [Member]
Fair Value Measurement Inputs and Valuation Techniques [Abstract]
Franchise Rights, Measurement Input			0.111
Franchise Rights [Member] | Nonrecurring [Member] | Minimum [Member] | Fair Value, Inputs, Level 3 [Member] | Measurement Input, Long-term Pretax Income Margin [Member] | Valuation Technique, Discounted Cash Flow [Member]
Fair Value Measurement Inputs and Valuation Techniques [Abstract]
Franchise Rights, Measurement Input			0.006
Franchise Rights [Member] | Nonrecurring [Member] | Minimum [Member] | Fair Value, Inputs, Level 3 [Member] | Measurement Input, Contributory Asset Charges [Member] | Valuation Technique, Discounted Cash Flow [Member]
Fair Value Measurement Inputs and Valuation Techniques [Abstract]
Franchise Rights, Measurement Input			0.042
Franchise Rights [Member] | Nonrecurring [Member] | Maximum [Member] | Fair Value, Inputs, Level 3 [Member] | Measurement Input, Discount Rate [Member] | Valuation Technique, Discounted Cash Flow [Member]
Fair Value Measurement Inputs and Valuation Techniques [Abstract]
Franchise Rights, Measurement Input			0.143
Franchise Rights [Member] | Nonrecurring [Member] | Maximum [Member] | Fair Value, Inputs, Level 3 [Member] | Measurement Input, Long-term Pretax Income Margin [Member] | Valuation Technique, Discounted Cash Flow [Member]
Fair Value Measurement Inputs and Valuation Techniques [Abstract]
Franchise Rights, Measurement Input			0.028
Franchise Rights [Member] | Nonrecurring [Member] | Maximum [Member] | Fair Value, Inputs, Level 3 [Member] | Measurement Input, Contributory Asset Charges [Member] | Valuation Technique, Discounted Cash Flow [Member]
Fair Value Measurement Inputs and Valuation Techniques [Abstract]
Franchise Rights, Measurement Input			0.121
Reported Value Measurement [Member] | Continuing Operations [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets held for sale				53,300,000	25,500,000
Reported Value Measurement [Member] | Discontinued Operations [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets held for sale in discontinued operations				$ 1,100,000	$ 8,000,000

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