Quarterly report pursuant to Section 13 or 15(d)

Summary of Unvested Stock Option Activity (Detail)

v3.10.0.1
Summary of Unvested Stock Option Activity (Detail) - $ / shares
shares in Thousands
 3 Months Ended 9 Months Ended
Sep. 30, 2018
Sep. 30, 2017
Sep. 30, 2018
Sep. 30, 2017
Weighted Average Grant Date Fair Value        
Granted $ 1.02 $ 1.93 $ 1.38 $ 4.32
Stock Options        
Shares        
Beginning Balance     846  
Granted     487  
Vested     (337)  
Forfeited or cancelled     (102)  
Ending Balance 894   894  
Weighted Average Grant Date Fair Value        
Beginning Balance     $ 3.14  
Granted     1.38  
Vested     3.40  
Forfeited or cancelled     2.58  
Ending Balance $ 2.15   $ 2.15