Note 6 - Share Capital (Tables)
12 Months Ended
Dec. 31, 2014
Note 6 - Share Capital (Tables) [Line Items]  
Schedule of Stockholders' Equity Note, Warrants or Rights [Table Text Block]
   

2014

   

2013

 
   

Shares
Underlying
Warrants

   

Shares
Underlying

Warrants

 

Balance, beginning of year

    10,922,090       5,922,090  

Warrants issued

          5,000,000  

Warrants expired

    (2,691,242 )      

Balance, end of year

    8,230,848       10,922,090  
Schedule of Earnings Per Share, Basic and Diluted [Table Text Block]
   

Years Ended December 31,

 
   

2014

   

2013

   

2012

 
   

(in thousands, except share and per share amounts)

 

Numerator:

                       

Net loss used to compute net loss per share

                       

Basic

  $ (49,963 )   $ (38,759 )   $ (3,415 )

Adjustments for change in fair value of warrant liability

                (25,520 )

Diluted

  $ (49,963 )   $ (38,759 )   $ (28,935 )
                         

Denominator:

                       

Weighted average shares outstanding used to compute net loss per share:

                       

Basic

    77,619,807       62,387,616       53,728,672  

Dilutive effect of warrants

                1,171,283  

Diluted

    77,619,807       62,387,616       54,899,955  

Net loss per share—basic

  $ (0.64 )   $ (0.62 )   $ (0.06 )

Net loss per share—diluted

  $ (0.64 )   $ (0.62 )   $ (0.53 )
Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table Text Block]
   

Years Ended December 31,

 
   

2014

   

2013

   

2012

 

Director and employee stock options

    5,217,535       4,415,033       2,934,453  

Warrants

    8,230,848       10,922,090       48,701  

Series A convertible preferred stock (as converted to common stock)

    10,000,000              

Non-employee director restricted share units

    163,204       191,613       140,968  

Employee stock purchase plan

    3,997       2,765       4,758  
Warrants Classified as Equity [Member]  
Note 6 - Share Capital (Tables) [Line Items]  
Schedule of Stockholders' Equity Note, Warrants or Rights [Table Text Block]
   


Years Ended December 31,

 
   

2014

   

2013

 

Shares underlying warrants outstanding classified as liabilities

    3,182,147       5,873,389  

Shares underlying warrants outstanding classified as equity

    5,048,701       5,048,701  
Warrants [Member]  
Note 6 - Share Capital (Tables) [Line Items]  
Schedule of Stockholders' Equity Note, Warrants or Rights [Table Text Block]

Exercise Prices

 

Shares
Underlying
Outstanding
Warrants

   

Expiry Date

$3.08

    48,701    

February 8, 2018

$4.24

    3,182,147    

October 12, 2015

$5.00

    5,000,000    

December 5, 2018

      8,230,848