Number of stores with franchise rights carrying values that exceeded their fair values in the quantitative impairment tests.

No definition available.

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Amount of loss from the write-down of an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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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.

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Amount of impairment loss resulting from write-down of assets, excluding financial assets and goodwill, lacking physical substance and having a projected indefinite period of benefit to fair value.

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Goodwill And Intangible Assets, Net (Narrative) (Details) $ in Millions	3 Months Ended					9 Months Ended
	Sep. 30, 2020 USD ($)	Jun. 30, 2020 USD ($)	Mar. 31, 2020 USD ($) store	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)
Goodwill [Line Items]
Goodwill impairment	$ 0.0			$ 0.0		$ 318.3	$ 0.0
Franchise rights impairment, number of stores \| store			8
Franchise rights impairment	$ 0.0			$ 0.0		57.5	9.6
Reporting Unit, Premium Luxury [Member]
Goodwill [Line Items]
Goodwill impairment						257.4
Reporting Unit, Collision Centers [Member]
Goodwill [Line Items]
Goodwill impairment						41.6
Reporting Unit, Parts Centers [Member]
Goodwill [Line Items]
Goodwill impairment						19.3
Fair Value, Nonrecurring [Member]
Goodwill [Line Items]
Goodwill impairment			$ 318.3			$ 318.3	$ 0.0
Fair Value, Nonrecurring [Member] \| Reporting Unit, Premium Luxury [Member]
Goodwill [Line Items]
Goodwill impairment			257.4
Fair Value, Nonrecurring [Member] \| Reporting Unit, Collision Centers [Member]
Goodwill [Line Items]
Goodwill impairment			41.6
Fair Value, Nonrecurring [Member] \| Reporting Unit, Parts Centers [Member]
Goodwill [Line Items]
Goodwill impairment			19.3
Fair Value, Nonrecurring [Member] \| Franchise Rights [Member]
Goodwill [Line Items]
Franchise rights impairment		$ 0.0	$ 57.5		$ 9.6