Annual report pursuant to Section 13 and 15(d)

Earnings Per Share - Additional Information (Detail)

v3.3.1.900
Earnings Per Share - Additional Information (Detail) - shares
12 Months Ended
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2013
Earnings Per Share [Line Items]      
Options excluded from the computation of diluted earnings 0 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