Annual report pursuant to Section 13 and 15(d)

Earnings Per Share - Additional Information (Detail)

v3.6.0.2
Earnings Per Share - Additional Information (Detail) - shares
12 Months Ended
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Earnings Per Share [Line Items]      
Options excluded from the computation of diluted earnings 346,912 0 0
Class A Common Stock [Member]      
Earnings Per Share [Line Items]      
Common stock, voting rights One vote per share    
Class B Common Stock [Member]      
Earnings Per Share [Line Items]      
Common stock, voting rights Ten votes per share