XML 75 R66.htm IDEA: XBRL DOCUMENT v3.19.3.a.u2
Basic and Diluted Earnings per Share - Additional Information (Detail) - shares
12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Class A | 2013 Plan      
Earnings Per Share [Line Items]      
Shares issuable under stock options excluded from calculation of diluted earnings per share 933,000 896,000 398,000