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 6 Months Ended
Jun. 30, 2017
Jun. 30, 2016
Jun. 30, 2017
Jun. 30, 2016
Weighted Average Grant Date Fair Value        
Granted $ 0.79 $ 0.97 $ 0.92 $ 0.90
Stock Options        
Shares        
Beginning Balance     3,259,000  
Granted     1,214,000  
Vested     (638,000)  
Forfeited or cancelled     (154,000)  
Ending Balance 3,681,000   3,681,000  
Weighted Average Grant Date Fair Value        
Beginning Balance     $ 1.16  
Granted     0.92  
Vested     1.09  
Forfeited or cancelled     1.21  
Ending Balance $ 1.09   $ 1.09