v3.8.0.1
Note 12 - Stock-based Compensation (Tables)
12 Months Ended
Dec. 31, 2017
Notes Tables  
Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Table Text Block]
   
December
31,
201
7
   
December
31,
201
6
   
December
31,
201
5
 
Cost of goods sold
  $
324
    $
302
    $
67
 
Research and development
   
1,901
     
2,308
     
2,587
 
General and administrative
   
2,069
     
1,869
     
2,356
 
Total
  $
4,294
    $
4,479
    $
5,010
 
Share-based Compensation, Stock Options, Activity [Table Text Block]
   
Number
of Stock Options
Outstanding
   
Weighted-
Average
Exercise
Price
   
Weighted-
Average
Remaining
Contractual
Life (Years)
   
Aggregate
Intrinsic
Value
 
   
 
 
 
 
 
 
 
 
 
 
 
 
(in
thousands)
 
December
31, 2016
   
6,307,756
    $
5.00
     
 
     
 
 
Granted
   
3,007,155
     
2.99
     
 
     
 
 
Forfeited
   
(438,519
)    
4.28
     
 
     
 
 
Expired
   
(351,922
)    
7.31
     
 
     
 
 
Exercised
   
(69,372
)    
1.52
     
 
     
 
 
December
31, 2017
   
8,455,098
    $
4.25
     
7.1
    $
13
 
Vested and exercisable options
—December 31, 2017
   
4,529,174
    $
5.11
     
5.56
    $
13
 
Vested and expected to vest
—December 31, 2017
   
8,455,098
    $
4.25
     
7.1
    $
13
 
Schedule of Share-based Compensation, Stock Options Outstanding and Exercisable Activity [Table Text Block]
       
Options Outstanding
   
Options
Vested and Exercisable
 
Exercise Prices
 
Number of
Stock Options
Outstanding
   
Weighted-Average
Remaining
Contractual Life
(Years)
   
Weighted-Average
Exercise Price per
Share
   
Shares
Subject
to Stock
Options
   
Weighted-Average
Exercise Price per
Share
 
$1.20
-
$2.
30
   
105,900
     
8.4
    $
2.13
     
38,400
    $
1.84
 
$2.
40
-
$3.77
   
5,592,633
     
7.7
    $
3.10
     
1,948,300
    $
3.17
 
$
3.92
-
$6.60
   
2,060,565
     
5.7
    $
5.45
     
1,880,190
    $
5.36
 
$8.18
-
$10.55
   
696,000
     
6.2
    $
10.28
     
662,284
    $
10.28
 
 
 
 
   
8,455,098
     
7.1
    $
4.25
     
4,529,174
    $
5.11
 
Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block]
   
Year
Ended December 31,
 
   
201
7
   
201
6
   
201
5
 
Expected term (in years)
 
5.70
   
5.25
-
6.25
   
5.25
-
6.25
 
Risk-free interest rate
 
 1.82%
-
2.09%
   
 1.24%
-
1.47%
   
 1.35%
-
1.82%
 
Expected volatility
 
73%
   
80%
   
72%
 
Expected dividend rate
 
0%
   
0%
   
0%