v3.8.0.1
Note 14 - Net Loss Per Share of Common Stock (Tables)
 12 Months Ended
Dec. 31, 2017
Notes Tables  
Schedule of Earnings Per Share, Basic and Diluted [Table Text Block]
   
Years Ended December
31,
  
   
201
7
    
201
6
    
201
5
  
   
(in thousands, except share and per share amounts)
  
Numerator:
                        
Net loss used to compute net loss per share
                        
Basic
   $
(51,508
)
   $
(43,157
)
   $
(24,399
)
Adjustments for change in fair value of warrant liability
    
—
      
—
      
(2,120
)
Diluted
   $
(51,508
)
   $
(43,157
)
   $
(26,519
)
Denominator:
                        
Weighted average shares outstanding used to compute net loss per share:
                        
Basic
    
46,883,535
      
45,313,118
      
44,300,099
  
Dilutive effect of warrants
    
—
      
—
      
168,341
  
Diluted
    
46,883,535
      
45,313,118
      
44,468,440
  
Net loss per share
—basic
   $
(1.10
)
   $
(0.95
)
   $
(0.55
)
Net loss per share
—diluted
   $
(1.10
)
   $
(0.95
)
   $
(0.60
)
Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table Text Block]
   
Year Ended December
31,
  
   
201
7
    
201
6
    
201
5
  
ESPP and stock options to purchase common stock
    
8,767,783
      
6,395,879
      
4,699,121
  
Convertible debt into common stock
    
—
      
553,763
      
553,763
  
Common stock warrants
    
176,730
      
692,611
      
180,155