Quarterly report pursuant to Section 13 or 15(d)

Earnings Per Share - Additional Information (Detail)

v3.19.2
Earnings Per Share - Additional Information (Detail) - shares
3 Months Ended 6 Months Ended
Jun. 30, 2019
Jun. 30, 2018
Jun. 30, 2019
Jun. 30, 2018
Earnings Per Share [Line Items]        
Options excluded from the computation of diluted earnings 237,035 232,164 195,677 195,041
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