Quarterly report pursuant to Section 13 or 15(d)

Summary of Unvested Stock Option Activity (Detail)

v3.19.1
Summary of Unvested Stock Option Activity (Detail) - $ / shares
shares in Thousands
3 Months Ended
Mar. 31, 2019
Mar. 31, 2018
Weighted Average Grant Date Fair Value    
Granted $ 1.53 $ 1.45
Stock Options    
Shares    
Beginning Balance 522  
Granted 40  
Vested (97)  
Forfeited or cancelled (56)  
Ending Balance 409  
Weighted Average Grant Date Fair Value    
Beginning Balance $ 2.11  
Granted 1.53  
Vested 3.52  
Forfeited or cancelled 3.00  
Ending Balance $ 1.59