XML 40 R26.htm IDEA: XBRL DOCUMENT v3.19.1
Note 7 - Stock-based Compensation (Tables)
 12 Months Ended
Dec. 31, 2018
Notes Tables  
Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Table Text Block]
    Year Ended December 31,
    2018   2017   2016
Research and development   $
6,867
     $
9,602
     $
6,088
  
General and administrative    
2,529
      
3,019
      
2,399
  
Total stock-based compensation expense   $
9,396
     $
12,621
     $
8,487
  
Share-based Compensation, Activity [Table Text Block]
    Awards
Available		   Options
Outstanding		   Weighted
Average
Exercise
Price
Balance at December 31, 2015    
16
      
10,671
     $
7.50
  
Plan amendment    
3,800
      
-
      
-
  
Restricted stock awards granted    
(34
 )    
-
      
-
  
Restricted stock awards cancelled    
22
      
-
      
-
  
Stock option awards granted    
(2,248
 )    
2,248
      
3.20
  
Stock option awards exercised    
-
      
(107
 )    
2.63
  
Stock option awards cancelled    
717
      
(717
 )    
10.78
  
Balance at December 31, 2016    
2,273
      
12,095
      
6.55
  
Plan amendment    
1,000
      
-
      
-
  
Restricted stock awards granted    
(22
 )    
-
      
-
  
Restricted stock awards cancelled    
12
      
-
      
-
  
Stock option awards granted    
(3,915
 )    
3,915
      
5.33
  
Stock option awards exercised    
-
      
(438
 )    
3.50
  
Stock option awards cancelled    
1,120
      
(1,120
 )    
9.72
  
Balance at December 31, 2017    
468
      
14,452
      
6.06
  
Plan amendment    
4,400
      
-
      
-
  
Restricted stock awards granted    
(13
 )    
-
      
-
  
Restricted stock awards cancelled    
-
      
-
      
-
  
Stock option awards granted    
(4,272
 )    
4,272
      
7.15
  
Stock option awards exercised    
-
      
(1,011
 )    
2.92
  
Stock option awards cancelled    
222
      
(222
 )    
7.44
  
Balance at December 31, 2018    
805
      
17,491
     $
6.49
  
Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block]
    2018   2017   2016
Expected Life    
5.5
      
5.5
      
5.5
  
Expected Volatility    
82
 %    
82
 %    
82
 %
Expected Dividend Yield    
0.0
 %    
0.0
 %    
0.0
 %
Risk-Free Interest Rate    
2.7
 %    
2.0
 %    
1.4
 %
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding and Exercisable [Table Text Block]
         
Outstanding
  
Exercisable
Range
      
Number
  
Weighted

Average

Remaining

Life
  
Weighted

Average

Exercise

Price
  
Number
  
Weighted

Average

Exercise

Price
$
0
to
3
  
1,266
    
4.1
    
$
1.66
      
1,191
    
$
1.58
  
 
3
to
6
  
7,778
    
6.8
      
4.69
      
3,937
      
4.50
  
 
6
to
9
  
4,768
    
8.7
      
7.06
      
883
      
6.85
  
 
9
to
12
  
2,980
    
6.5
      
10.90
      
1,711
      
10.96
  
 
12
to
15
  
604
    
6.0
      
12.29
      
403
      
12.35
  
 
15
to
18
  
95
    
6.5
      
15.39
      
71
      
15.39
  
$
0
to
18
  
17,491
    
7.0
    
$
6.49
      
8,196
    
$
6.16
  
Share-based Compensation, Stock Options, Activity [Table Text Block]
    Non-Vested
Stock Option
Awards		   Weighted Average
Grant-Date Fair
Value
Balance December 31, 2017    
7,202
     $
4.56
  
Stock option awards granted    
4,272
      
4.92
  
Stock option awards vested    
(2,065
 )    
4.33
  
Stock option awards forfeited    
(114
 )    
4.12
  
Balance December 31, 2018    
9,295
     $
4.78