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Acquisitions (Details) $ in Millions	12 Months Ended
	Dec. 31, 2016 USD ($) stores	Dec. 31, 2015 stores	Dec. 31, 2014 stores
Business Acquisition [Line Items]
Goodwill	$ 140.4
Number of stores purchased | stores	20	22	5
Actual Revenue included in consolidated results	$ 790.5
Actual net income included in consolidated results	21.7
Reporting Unit, Domestic [Member]
Business Acquisition [Line Items]
Goodwill	57.9
Reporting Unit, Import [Member]
Business Acquisition [Line Items]
Goodwill	2.0
Reporting Unit, Premium Luxury [Member]
Business Acquisition [Line Items]
Goodwill	76.9
Goodwill Corporate and Other [Member]
Business Acquisition [Line Items]
Goodwill	$ 3.6

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- Definition

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- Definition

The amount of goodwill arising from a business combination that is expected to be deductible for tax purposes.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=35744584&loc=d3e6927-128479

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- Definition

This element represents the amount of earnings or loss of the acquiree since the acquisition date included in the consolidated income statement for the reporting period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (h)(1)
-URI http://asc.fasb.org/extlink&oid=65885119&loc=d3e1392-128463

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- Definition

This element represents the amount of revenue of the acquiree since the acquisition date included in the consolidated income statement for the reporting period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (h)(1)
-URI http://asc.fasb.org/extlink&oid=65885119&loc=d3e1392-128463

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- Definition

The number of businesses acquired by the entity during the period.

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