Note 7 - Share-based Compensation (Details) (USD $)
12 Months Ended 1 Months Ended 6 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Jun. 30, 2014
Jun. 30, 2014
Sep. 30, 2014
Jun. 03, 2010
Note 7 - Share-based Compensation (Details) [Line Items]              
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested in Period, Fair Value (in Dollars) $ 6,290,000 $ 4,730,000 $ 2,930,000        
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period 6,000   2,655        
Share Price (in Dollars per share) $ 1.90            
Value Shares Withheld Restricted Share Unit Percentage 25.00%            
Shares for Tax Withholding for Restricted Share Unit Plan     10,846        
Employee Stock Option [Member] | Begin to Vest [Member] | Options Granted Prior to January 2010 [Member] | Stock Option Plan [Member]              
Note 7 - Share-based Compensation (Details) [Line Items]              
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period 1 year            
Employee Stock Option [Member] | Options Granted Prior to January 2010 [Member] | Stock Option Plan [Member]              
Note 7 - Share-based Compensation (Details) [Line Items]              
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period 4 years            
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period 8 years            
Employee Stock Option [Member] | Options Granted After January 2010 [Member] | Stock Option Plan [Member]              
Note 7 - Share-based Compensation (Details) [Line Items]              
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period 36 months            
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period 8 years            
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage 25.00%            
Employee Stock Option [Member] | Stock Option Plan [Member]              
Note 7 - Share-based Compensation (Details) [Line Items]              
Maximum Fixed Reloading Percentage 10.00%            
Common Stock, Capital Shares Reserved for Future Issuance 9,160,135            
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant 1,825,858            
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period   0          
Employee Stock Option [Member]              
Note 7 - Share-based Compensation (Details) [Line Items]              
Share Based Compensation Arrangement by Share Based Payment Award Options in the Money Exercisable Number 535,188            
Allocated Share-based Compensation Expense (in Dollars) 1,700,000 1,700,000 1,400,000        
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized (in Dollars) 3,300,000            
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition 35 months            
Restricted Stock Units (RSUs) [Member] | Maximum [Member] | Restricted Share Unit Plan [Member]              
Note 7 - Share-based Compensation (Details) [Line Items]              
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period 5 years            
Restricted Stock Units (RSUs) [Member] | Restricted Share Unit Plan [Member]              
Note 7 - Share-based Compensation (Details) [Line Items]              
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant           530,910  
Allocated Share-based Compensation Expense (in Dollars) 400,000 (200,000) 500,000        
Restricted Stock Unit, Shares Issued Per Unit Upon Conversion 1            
Share-based Compensation Arrangement by Share-based Payment Award, Number of Additional Shares Authorized 500,000     500,000      
Restricted Share Units Maximum Shares Reserved 966,666            
Value Shares Withheld Restricted Share Unit Percentage         25.00%    
Share-based Compensation Arrangement by Share-based Payment Award, Shares Issued in Period 110,104 46,906 43,397        
Restricted Stock Units (RSUs) [Member]              
Note 7 - Share-based Compensation (Details) [Line Items]              
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period 110,104 46,906 43,397        
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value (in Dollars per share)   $ 1.84 $ 3.55        
Shares for Tax Withholding for Restricted Share Unit Plan   11,730          
Restricted Share Unit Plan [Member] | Non-Employee Director Restricted Share Units [Member]              
Note 7 - Share-based Compensation (Details) [Line Items]              
Cash Paid for Tax Withholding for Share Based Compensation (in Dollars) 95,653 21,636 38,544        
Restricted Share Unit Plan [Member]              
Note 7 - Share-based Compensation (Details) [Line Items]              
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value (in Dollars per share) $ 3.47            
Shares for Tax Withholding for Restricted Share Unit Plan 27,528            
Employee Stock Purchase Plan [Member]              
Note 7 - Share-based Compensation (Details) [Line Items]              
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant 600,533            
Allocated Share-based Compensation Expense (in Dollars) 101,796 149,674 184,960        
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized (in Dollars) 25,559            
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition 255 days            
Price 1 [Member] | Employee Stock Purchase Plan [Member]              
Note 7 - Share-based Compensation (Details) [Line Items]              
Stock Issued During Period, Shares, Employee Stock Purchase Plans   38,934 49,086        
Employee Stock Purchase Plan Purchase Price (in Dollars)   1.46 3.33        
Price 2 [Member] | Employee Stock Purchase Plan [Member]              
Note 7 - Share-based Compensation (Details) [Line Items]              
Stock Issued During Period, Shares, Employee Stock Purchase Plans   35,895 6,338        
Employee Stock Purchase Plan Purchase Price (in Dollars)   1.57 2.82        
Employee Stock Purchase Plan [Member]              
Note 7 - Share-based Compensation (Details) [Line Items]              
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Intrinsic Value (in Dollars) 0            
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized 900,000           900,000
Employee Stock Purchase Plan Interval Period 6 years            
Share-based Compensation Arrangement by Share-based Payment Award, Maximum Employee Subscription Rate 15.00%            
Employee Stock Purchase Plan Maximum Value Of Compensation Per Employee (in Dollars) 25,000            
Employee Stock Purchase Plan Purchase Of Common Stock Percentage 85.00%            
Share-based Compensation Arrangement by Share-based Payment Award, Maximum Number of Shares Per Employee 15,000            
Stock Issued During Period, Shares, Employee Stock Purchase Plans 76,811            
Employee Stock Purchase Plan Purchase Price (in Dollars) $ 1.49