Note 3 - Acquisitions (Details Textual) - USD ($)
Nov. 12, 2019
Aug. 08, 2019
Apr. 01, 2019
Mar. 31, 2020
Dec. 31, 2019
Nov. 11, 2019
Aug. 07, 2019
Mar. 31, 2019
Goodwill, Ending Balance       $ 33,506,000 $ 33,637,000      
Equity Method Investments       $ 27,000      
SAVSU [Member]                
Equity Method Investments   $ 5,800,000            
Astero [Member]                
Payments to Acquire Businesses, Gross     $ 12,521,000          
Payments to Acquire Businesses, Initial Cash Payment     8,000,000          
Payments to Acquire Businesses, Deferred Cash Payment     4,500,000          
Business Combination, Consideration Transferred, Liabilities Incurred     1,491,000          
Business Combination, Contingent Consideration Arrangements, Range of Outcomes, Value, High     8,500,000          
Business Combination, Contingent Consideration, Liability, Total     1,500,000          
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net Tangible Assets     324,000          
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Indefinite-Lived Intangible Assets     4,100,000          
Goodwill, Ending Balance     9,515,000         $ 9,500,000
Business Acquisition, Goodwill, Expected Tax Deductible Amount     1,100,000          
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net, Total     13,941,000          
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles     12,150,000         $ 4,120,000
Business Combination, Consideration Transferred, Total     13,941,000          
Astero [Member] | Earnout Payments Payable in Each Calendar Years of 2019, 2020 and 2021 [Member]                
Business Combination, Consideration Transferred, Liabilities Incurred     3,500,000          
Astero [Member] | Earnout Payment for Calendar Year 2021 [Member]                
Business Combination, Consideration Transferred, Liabilities Incurred     $ 5,000,000          
SAVSU [Member]                
Goodwill, Ending Balance   $ 19,500,000         $ 21,037,000  
Business Combinations, Number of Shares Acquired (in shares)   8,616            
Business Acquisition, Percentage of Voting Interests Acquired   55.60%            
Business Acquisition, Equity Interest Issued or Issuable, Number of Shares (in shares)   1,100,000            
Share Price (in dollars per share)   $ 18.12            
Business Combination, Consideration Transferred, Equity Interests Issued and Issuable   $ 19,932,000            
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net, Total   35,800,000         $ 35,850,000  
Business Combination, Step Acquisition, Equity Interest in Acquiree, Fair Value   $ 15,900,000            
Business Combination, Step Acquisition, Equity Interest in Acquiree, Percentage   44.00%            
Business Combination, Step Acquisition, Equity Interest in Acquiree, Remeasurement Gain (Loss), Net, Total   $ 10,100,000            
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Tangible Assets, Net   4,200,000            
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles   12,200,000            
Business Combination, Consideration Transferred, Including Equity Interest in Acquiree Held Prior to Combination, Total   $ 35,800,000            
CBS Acquisition [Member]                
Payments to Acquire Businesses, Gross $ 11,000,000              
Payments to Acquire Businesses, Initial Cash Payment 11,000,000              
Business Combination, Consideration Transferred, Liabilities Incurred 856,000              
Goodwill, Ending Balance 3,100,000         $ 2,954,000    
Business Combination, Consideration Transferred, Equity Interests Issued and Issuable 4,000,000              
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net, Total           15,856,000    
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Tangible Assets, Net 6,000,000              
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles 6,800,000         $ 6,790,000    
Business Combination, Consideration Transferred, Total 15,856,000              
Business Combination, Cash Holdback Escrow to Satisfy Indemnification Claims 550,000              
Business Combination, Consideration Transferred, Equity Interests Issued and Issuable, Escrow Holdback 3,000,000              
CBS Acquisition [Member] | Earning Payments Payable in Each Calendar Year 2020, 2021, 2022, 2023, and 2024 [Member]                
Business Combination, Contingent Consideration Arrangements, Range of Outcomes, Value, High $ 15,000,000