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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 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 + Details
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