Note 11 - Stock Option and Equity Incentive Plans (Tables)
 12 Months Ended
Dec. 31, 2016
Notes Tables  
Schedule of Share-based Compensation, Stock Options, Activity [Table Text Block]
    Shares Under
Options		  
Weighted
Average
Exercise
Price

 (per share)
  
Weighted
Average
Remaining
Contractual
Life

(in years)		  
Aggregate
Intrinsic
Value

(in thousands)
                 
Outstanding December 31, 2015    
270,205
     $
15.40
      
 
      
 
  
Granted    
17,184
      
22.02
      
 
      
 
  
Exercised    
(54,811
 )    
24.57
      
 
      
 
  
Outstanding December 31, 2016    
232,578
     $
16.53
      
3.66
     $
2,074
  
Exercisable at December 31, 2016    
210,078
     $
16.02
      
3.86
     $
1,981
  
Vested and expected to vest at December 31, 2016    
232,578
     $
16.53
      
3.66
     $
2,074
  
Schedule of Share-based Compensation, Restricted Stock Units Award Activity [Table Text Block]
    Restricted
Stock Units		   Weighted
Average Award
Date Fair Value
Outstanding at December 31, 2015    
40,645
     $
19.67
  
Awarded    
17,822
      
21.66
  
Shares vested    
(11,909
 )    
20.94
  
Outstanding at December 31, 2016    
46,558
     $
20.05
  
Schedule of Future Share-based Compensation Expense [Table Text Block]
    Options   Common
Stock		   Restricted
Stock Units		   Total
2017    
44
      
-
      
293
      
337
  
2018    
16
      
-
      
207
      
223
  
2019    
-
      
-
      
110
      
110
  
2020    
-
      
-
      
23
      
23
  
Total   $
60
     $
-
     $
633
     $
693