XML 64 R52.htm IDEA: XBRL DOCUMENT v3.8.0.1
Earnings Per Share - Additional Information (Detail) - shares
3 Months Ended
Mar. 31, 2018
Mar. 31, 2017
Stock options    
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]    
Stock options not included in computation of diluted earnings per share 1,191,744 1,366,256
Restricted stock units    
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]    
Stock options not included in computation of diluted earnings per share 296,058 821,756