Annual report pursuant to Section 13 and 15(d)

Net Loss Per Share - Additional Information (Detail)

v3.8.0.1
Net Loss Per Share - Additional Information (Detail) - shares
shares in Millions
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Earnings Per Share [Abstract]      
Common stock equivalents excluded from the calculation of net loss per share (shares) 4.5 0.8 3.0