Annual report pursuant to Section 13 and 15(d)

STOCK-BASED COMPENSATION - Assumptions (Details)

v3.7.0.1
STOCK-BASED COMPENSATION - Assumptions (Details)
 12 Months Ended
Dec. 31, 2016
USD ($)
item
$ / shares
shares
Dec. 31, 2015
USD ($)
$ / shares
shares
Dec. 31, 2014
USD ($)
$ / shares
Dec. 31, 2016
USD ($)
$ / shares
shares
Dec. 31, 2015
USD ($)
shares
Stock Based Compensation          
Number of homogenous groups for purposes of determining fair values of options | item 3        
Share-based compensation | $ $ 7,832,000 $ 7,403,000 $ 9,787,000    
Employee stock purchase plan          
Weighted-average assumptions relating to options granted          
Risk-free interest rate (as a percent) 0.50% 0.60% 0.30%    
Expected term (in years) 1 year 6 months 1 year 6 months 1 year 8 months 12 days    
Dividend yield (as a percent) 0.00% 0.00% 0.00%    
Expected volatility (as a percent) 62.90% 61.20% 66.00%    
Employee stock option          
Stock Based Compensation          
Contractual term of the option 10 years        
Weighted-average assumptions relating to options granted          
Risk-free interest rate (as a percent) 1.80% 1.80% 2.20%    
Expected term (in years) 6 years 2 months 12 days 6 years 6 months 6 years 6 months    
Dividend yield (as a percent) 0.00% 0.00% 0.00%    
Expected volatility (as a percent) 61.10% 65.00% 74.40%    
Shares Available For Grant          
Outstanding at the beginning of the period (in shares) 5,245,977        
Authorized for grant (in shares) 2,790,000        
Granted (in shares) (5,251,185) (3,875,170)      
Cancelled (in shares) 3,763,904        
Outstanding at the end of the period (in shares) 6,548,696 5,245,977      
Number of Shares Underlying Options          
Outstanding at the beginning of the period (in shares) 19,106,472        
Granted (in shares) 5,251,185 3,875,170      
Exercised (in shares) (336,520)        
Cancelled (in shares) (3,763,904)        
Outstanding at the end of the period (in shares) 20,257,233 19,106,472      
Vested and expected to vest (in shares)       20,032,758  
Exercisable (in shares)       16,588,341  
Weighted Average Exercise Price          
Outstanding at the beginning of the period (in dollars per share) | $ / shares $ 7.08        
Granted (in dollars per share) | $ / shares 2.98        
Exercised (in dollars per share) | $ / shares 2.30        
Cancelled (in dollars per share) | $ / shares 6.32        
Outstanding at the end of the period (in dollars per share) | $ / shares $ 6.24 $ 7.08      
Vested and expected to vest (in dollars per share) | $ / shares       $ 6.27  
Exercisable (in dollars per share) | $ / shares       $ 6.93  
Weighted Average Remaining Contractual Term (in years)          
Outstanding at the end of the period 5 years 15 days        
Exercisable 4 years 1 month 10 days        
Aggregate Intrinsic Value          
Outstanding at the end of the period (in dollars) | $       $ 727,727  
Exercisable | $       $ 696,655  
Number of nonvested stock options (in shares)       3,668,891 4,017,340
Intrinsic value of nonvested stock options | $       $ 31,000 $ 2,200,000
Aggregate intrinsic value of options exercised | $ $ 253,000 $ 252,000      
Unrecognized compensation cost related to purchase plan | $       $ 639,000  
Weighted-average recognition period of unamortized compensation cost 2 years 8 months 12 days 10 months 24 days      
Number of shares vested 4,215,058 2,326,021      
Weighted-average exercise price for shares vested during the period (in dollars per share) | $ / shares $ 2.70 $ 3.13      
Additional disclosures          
Options cancelled (in shares) 3,763,904        
Options outstanding at the end of the period (in shares) 19,106,472 19,106,472   20,257,233 19,106,472
Grant-date weighted-average fair value (in dollars per share) | $ / shares $ 1.72 $ 1.40 $ 2.32    
Total unrecognized compensation cost, net of estimated forfeitures | $       $ 5,000,000  
Shares of common stock available for future grant 5,245,977 5,245,977   6,548,696 5,245,977
Options exercised during the period (in shares) 336,520        
Employee stock option | Consultant          
Stock Based Compensation          
Contractual term of the option 10 years        
Performance shares          
Shares Available For Grant          
Granted (in shares)   (1,175,000)      
Number of Shares Underlying Options          
Granted (in shares)   1,175,000      
Performance shares | Corporate performance-based milestone          
Stock Based Compensation          
Share-based compensation | $ $ 1,100,000        
Shares Available For Grant          
Granted (in shares) (700,000)        
Number of Shares Underlying Options          
Granted (in shares) 700,000        
Additional disclosures          
Grant date fair value of performance stock options awards | $ $ 1,100,000        
Performance shares | Other corporate performance-based milestones          
Stock Based Compensation          
Share-based compensation | $ $ 0        
Shares Available For Grant          
Granted (in shares) (100,000)        
Number of Shares Underlying Options          
Granted (in shares) 100,000        
Additional disclosures          
Grant date fair value of performance stock options awards | $ $ 232,000        
Performance shares | Corporate sales target          
Stock Based Compensation          
Share-based compensation | $ $ 0        
Shares Available For Grant          
Granted (in shares) (100,000)        
Number of Shares Underlying Options          
Granted (in shares) 100,000        
Additional disclosures          
Grant date fair value of performance stock options awards | $ $ 240,000        
Performance shares | Awards granted in 2014          
Stock Based Compensation          
Share-based compensation | $ $ 520,000        
Number of Shares Underlying Options          
Outstanding at the end of the period (in shares) 200,000        
Additional disclosures          
Options outstanding at the end of the period (in shares) 200,000     200,000  
Grant date fair value of performance stock options awards | $     $ 520,000