Note 11 - Income Taxes (Tables)
 12 Months Ended
Mar. 31, 2017
Notes Tables  
Schedule of Income before Income Tax, Domestic and Foreign [Table Text Block]
 
 
Year Ended March 31,
 
 
 
2017
 
 
2016
 
 
2015
 
Domestic
   $
12,913
     $
14,427
     $
14,896
  
Foreign
    
1,383
      
1,128
      
451
  
    $
14,296
     $
15,555
     $
15,347
  
Schedule of Components of Income Tax Expense (Benefit) [Table Text Block]
 
 
Year Ended March 31,
 
 
 
2017
 
 
2016
 
 
2015
 
Current tax provision
                        
Federal
   $
2,282
     $
3,666
     $
4,186
  
State
    
510
      
627
      
1,135
  
Foreign
    
849
      
658
      
212
  
     
3,641
      
4,951
      
5,533
  
Deferred tax provision:
                        
Federal
    
(126
 )    
(189
 )    
252
  
State
    
(32
 )    
(138
 )    
51
  
Foreign
    
(370
 )    
(238
 )    
(72
 )
     
(528
 )    
(565
 )    
231
  
    $
3,113
     $
4,386
     $
5,764
  
Schedule of Deferred Tax Assets and Liabilities [Table Text Block]
 
 
March 31,
 
 
 
201
7
 
 
201
6
 
Current deferred tax assets:
                
Accrued employee-related expenses
   $
242
    $
257
 
Allowances and reserves
    
132
      
217
  
Stock option deductible differences
    
898
      
606
  
Inventory
    
691
      
533
  
Currency translation adjustment
    
--
      
12
  
Net operating loss
    
--
      
110
  
Other
    
9
      
3
  
     
1,972
      
1,738
  
                 
Long-term deferred tax liability:
                
Property, plant and equipment
    
(1,635
 )    
(1,599
 )
Goodwill and intangible assets
    
(3,807
 )    
(4,335
 )
Currency translation adjustment
    
(3
 )    
--
  
Other
    
(81
 )    
(5
 )
     
(5,526
 )    
(5,939
 )
                 
Net deferred tax liability
   $
(3,554
 )   $
(4,201
 )
Schedule of Effective Income Tax Rate Reconciliation [Table Text Block]
 
 
Year Ended March 31,
 
 
 
2017
 
 
2016
 
 
2015
 
Federal income taxes at statutory rates
   $
4,861
     $
5,445
     $
5,374
  
State income taxes, net of federal benefit
    
302
      
293
      
860
  
Tax benefit of stock option exercises
    
(1,576
 )    
(751
 )    
209
  
Section 199 manufacturing deduction
    
(304
 )    
(440
 )    
(317
 )
Research and development credit
    
(385
 )    
(345
 )    
(248
 )
Other
    
215
      
184
      
(114
 )
    $
3,113
     $
4,386
     $
5,764
  
Schedule of Unrecognized Tax Benefits Roll Forward [Table Text Block]
 
 
Year Ended March 31,
 
 
 
2017
 
 
2016
 
 
2015
 
Beginning balance
  $
221
     $
--
     $
--
  
Increases related to current period tax positions
    
110
      
221
      
--
  
Ending balance
   $
331
     $
221
     $
--