Annual report pursuant to Section 13 and 15(d)

Net Income (Loss) Per Share - Additional Information (Detail)

v3.8.0.1
Net Income (Loss) Per Share - Additional Information (Detail) - $ / shares
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
May 23, 2017
Earnings Per Share [Abstract]        
Shares excluded from dilutive shares outstanding because their effect was anti-dilutive 193,274 220,473 912,257  
Exercise price of warrants (in dollars per share)       $ 57.58