Quarterly report pursuant to Section 13 or 15(d)

Business Acquisitions and Dispositions - Additional Information (Detail)

v2.4.0.8
Business Acquisitions and Dispositions - Additional Information (Detail) (USD $)
In Millions, unless otherwise specified
3 Months Ended 9 Months Ended
Sep. 30, 2014
Franchise
Sep. 30, 2014
Franchise
Mar. 31, 2014
Dealerships
Business Acquisition [Line Items]      
Aggregate purchase price of franchise   $ 15.3  
Number of dealerships held for sale     0
Number of franchises disposed 2 5  
Cash generated from disposition $ 14.9 $ 30.1  
Number of franchise held for sale 1 1  
Mid-line Import Franchise [Member]
     
Business Acquisition [Line Items]      
Number of franchise acquired 1    
Luxury Franchise [Member]
     
Business Acquisition [Line Items]      
Number of franchise acquired   1