Note 3 - Fair Value Measurements (Tables)
12 Months Ended
Dec. 31, 2014
Fair Value Disclosures [Abstract]  
Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block]
   

December 31, 2014

   

December 31, 2013

 
   

Level 1

   

Level 2

   

Level 3

   

Total

   

Level 1

   

Level 2

   

Level 3

   

Total

 
   

(In thousands)

 

Financial Assets:

                                                               

Money market funds

  $ 4,103     $     $     $ 4,103     $ 6,058     $     $     $ 6,058  

Debt securities of U.S. government agencies

          43,844             43,844             49,890             49,890  

Corporate bonds

          9,416             9,416             13,393             13,393  
    $ 4,103     $ 53,260     $     $ 57,363     $ 6,058     $ 63,283     $     $ 69,341  

Financial Liability:

                                                               

Restricted Share Units

  $ 310     $     $     $ 310     $ 337     $     $     $ 337  

Warrants

                128       128                   924       924  
Fair Value Inputs, Liabilities, Quantitative Information [Table Text Block]
   

As of December 31, 2014

 
   

September 2010
Warrants

 

Exercise price

  $ 4.24  

Market value of stock at end of period

  $ 1.90  

Expected dividend rate

    0.0 %

Expected volatility

    60.3 %

Risk-free interest rate

    0.2 %

Expected life (in years)

    0.78  
   

As of December 31, 2013

 
   

May 2009
Warrants

   

September 2010
Warrants

 

Exercise price

  $ 3.74     $ 4.24  

Market value of stock at end of period

  $ 1.76     $ 1.76  

Expected dividend rate

    0.0 %     0.0 %

Expected volatility

    45.3 %     77.4 %

Risk-free interest rate

    0.1 %     0.3 %

Expected life (in years)

    0.40       1.78  
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Table Text Block]
   

Years Ended December 31,

 
   

2014

   

2013

 
   

(In thousands)

 

Balance at beginning of period

  $ 924     $ 3,251  

Change in fair value of warrant liability included in

               

Other expense (income)

    (796 )     (2,327 )

Balance at the end of period

  $ 128     $ 924