Annual report pursuant to Section 13 and 15(d)

Annual report pursuant to Section 13 and 15(d)

Stock Compensation - Roll Forward of Non-Vested Stock Options Activity (Detail)

v3.10.0.1
Stock Compensation - Roll Forward of Non-Vested Stock Options Activity (Detail) - $ / shares
12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]      
Number of options, outstanding 4,239,185    
Granted 2,457,102 2,119,498 2,617,526
Number of options, vested (2,039,176)    
Number of options, forfeited (326,585)    
Number of options, outstanding 4,330,526 4,239,185  
Weighted average granted date fair value, outstanding (in dollars per share) $ 2.29    
Weighted average granted date fair value, granted (in dollars per share) 2.80    
Weighted average granted date fair value, vested (in dollars per share) 2.69    
Weighted average granted date fair value, forfeited (in dollars per share) 2.97    
Weighted average granted date fair value, outstanding (in dollars per share) $ 2.67 $ 2.29