Note 2 - Acquisitions and Dispositions - Purchase Price Allocation (Details) - USD ($)
 12 Months Ended
Aug. 06, 2015
Jul. 06, 2015
Oct. 15, 2014
Mar. 31, 2017
Mar. 31, 2016
Mar. 31, 2015
Apr. 15, 2015
Apr. 15, 2014
Cash consideration       $ 6,800,000 $ 24,111,000 $ 20,543,000    
Goodwill       $ 72,156,000 $ 66,137,000 $ 44,869,000    
Infitrak Acquisition [Member]                
Total purchase price allocation   $ 18,655,000            
Cash consideration   8,747,000            
Holdback payment liability   637,000            
Contingent consideration liability   9,271,000            
Aggregate consideration   18,655,000            
Accounts receivable   925,000            
Inventories   310,000            
Property, plant and equipment   530,000            
Intangibles   5,869,000            
Goodwill   13,833,000            
Accounts payable   (470,000)            
Accrued liabilities   (767,000)            
Deferred income taxes   $ (1,575,000)            
North Bay Acquisition [Member]                
Unearned revenues $ (1,613,000)              
Total purchase price allocation 11,322,000              
Cash consideration 10,322,000              
Holdback payment liability 1,000,000              
Aggregate consideration 11,322,000              
Cash 20,000              
Accounts receivable 285,000              
Inventories 85,000              
Property, plant and equipment 229,000              
Intangibles 4,454,000              
Goodwill 7,962,000              
Accrued liabilities $ (100,000)              
PCD Acquisition [Member]                
Accrued expenses     $ (15,000)          
Total purchase price allocation     5,550,000          
Cash consideration     5,000,000          
Holdback payment liability     250,000          
Contingent consideration liability     300,000          
Aggregate consideration     5,550,000          
Inventories     137,000          
Property, plant and equipment     7,000          
Intangibles     3,678,000          
Goodwill     $ 1,743,000          
BGI [Member]                
Accrued expenses             $ (53,000)  
Total purchase price allocation             10,268,000 $ 10,268,000
Inventories             1,268,000  
Property, plant and equipment             47,000  
Intangibles             5,711,000  
Goodwill             $ 3,295,000