Annual report pursuant to Section 13 and 15(d)

Earnings per Share - Additional Information (Detail)

v3.8.0.1
Earnings per Share - Additional Information (Detail) - shares
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Stock option awards [Member]      
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]      
Anti-dilutive shares 0 74,389 30,250