Quarterly report pursuant to Section 13 or 15(d)

Summary of Significant Accounting Policies - Additional Information (Detail)

v3.4.0.3
Summary of Significant Accounting Policies - Additional Information (Detail)
 3 Months Ended
Mar. 31, 2016
Mar. 31, 2015
Dec. 31, 2015
Significant Accounting Policies [Line Items]      
Effective tax rate from continuing operations 38.80% 39.00%  
Minimum [Member]      
Significant Accounting Policies [Line Items]      
Expected effective tax rate for continuing operations Range 38.00%    
Maximum [Member]      
Significant Accounting Policies [Line Items]      
Expected effective tax rate for continuing operations Range 40.00%    
Dealership [Member]      
Significant Accounting Policies [Line Items]      
Percentage of dealership that is accounted for under the equity method 50.00%   50.00%