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Business Acquisitions and Dispositions - Additional Information (Details)

v3.10.0.1
Business Acquisitions and Dispositions - Additional Information (Details)
$ in Thousands
6 Months Ended
Jun. 30, 2018
USD ($)
Franchise
Business
Jun. 30, 2017
USD ($)
Franchise
Business
Business Combinations [Abstract]    
Number of acquired franchises | Business 0 0
Business Acquisition [Line Items]    
Number of franchises disposed   0
Proceeds from sales of dealerships | $ $ 122,404 $ 0
Number of franchises terminated 1  
Luxury franchise    
Business Acquisition [Line Items]    
Number of franchises disposed 6  
Pre-Owned Stores Segment    
Business Acquisition [Line Items]    
Number of franchises ceased operations 1