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
shares in Millions
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Restricted Stock    
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]    
Antidilutive securities excluded from computation of earnings per share amount 19.9 11.5