Quarterly report pursuant to Section 13 or 15(d)

Summary of Significant Accounting Policies - Additional Information (Detail)

v3.7.0.1
Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($)
$ in Thousands
 3 Months Ended 6 Months Ended
Jun. 30, 2017
Jun. 30, 2016
Jun. 30, 2017
Jun. 30, 2016
Dec. 31, 2016
Significant Accounting Policies [Line Items]          
Effective tax rate from continuing operations 39.30% 39.60% 39.80% 39.30%  
Income tax benefit $ (7,956) $ (15,113) $ (8,128) $ (24,283)  
ASU 2016-09 [Member]          
Significant Accounting Policies [Line Items]          
Income tax benefit $ 200   $ 500    
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%   50.00%