Annual report pursuant to Section 13 and 15(d)

Incentive Stock Plan - Stock Option Activity (Details)

v3.6.0.2
Incentive Stock Plan - Stock Option Activity (Details) - USD ($)
 12 Months Ended
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Additional option disclosures      
Total future stock compensation expense related to nonvested awards $ 5,800,000    
Weighted average period of recognition of future stock compensation expense 2 years 8 months 16 days    
Employee Consultants and Directors Stock Options [Member]      
Stock option activity      
Options, Outstanding at the beginning of the period (in shares) 3,228,027 2,743,818  
Options, Granted (in shares) 1,529,850 946,250  
Options, Forfeited (in shares) (75,938) (290,478)  
Options, Exercised (in shares) (340,942) (171,563)  
Options, Outstanding at the end of the period (in shares) 4,340,997 3,228,027 2,743,818
Options, Exercisable (in shares) 2,219,671    
Weighted Average Exercise Price, Outstanding at the beginning of the period (in dollars per share) $ 3.40 $ 3.03  
Weighted Average Exercise Price, Granted (in dollars per share) 7.67 4.31  
Weighted Average Exercise Price, Forfeited (in dollars per share) (3.74) (3.12)  
Weighted Average Exercise Price, Exercised (in dollars per share) (3.16) (2.99)  
Weighted Average Exercise Price, Outstanding at the end of the period (in dollars per share) 4.92 $ 3.40 $ 3.03
Weighted Average Exercise Price, Exercisable (in dollars per share) $ 3.19    
Weighted Average Remaining Contractual Term, Outstanding 5 years 11 months 5 days 5 years 5 months 5 days 5 years 11 months 9 days
Weighted Average Remaining Contractual Term, Exercisable 7 years 9 months 29 days    
Additional option disclosures      
Average fair value of options granted $ 7.67 $ 4.31  
Intrinsic value of options exercised $ 1,496,000 $ 370,000  
Intrinsic value of options outstanding 17,729,000 5,167,000  
Intrinsic value of options exercisable $ 12,894,000 $ 4,265,000  
Stock Options, Contingent Upon Optionee Re-election to Board of Directors [Member]      
Stock option activity      
Options, Granted (in shares) 25,000