Quarterly report pursuant to Section 13 or 15(d)

Summary of Unvested Stock Option Activity (Detail)

v3.7.0.1
Summary of Unvested Stock Option Activity (Detail) - $ / shares
3 Months Ended
Mar. 31, 2017
Mar. 31, 2016
Weighted Average Grant Date Fair Value    
Granted $ 1.05 $ 0.67
Stock Options    
Shares    
Beginning Balance 3,259,000  
Granted 611,000  
Vested (304,000)  
Forfeited or cancelled (131,000)  
Ending Balance 3,435,000  
Weighted Average Grant Date Fair Value    
Beginning Balance $ 1.16  
Granted 1.05  
Vested 1.10  
Forfeited or cancelled 1.23  
Ending Balance $ 1.15