Quarterly report pursuant to Section 13 or 15(d)

Note 2 - Revenue (Details Textual)

v3.20.2
Note 2 - Revenue (Details Textual)
3 Months Ended 6 Months Ended
Jun. 30, 2020
USD ($)
Jun. 30, 2019
Jun. 30, 2020
Jun. 30, 2019
Revenue from Contract with Customers, Sales Returns, Percent     2.00% 2.00%
Contract with Customer, Liability, Revenue Recognized $ 1,900,000      
Contract with Customer Liability, Increase from Cash Receipts $ 565,000      
Geographic Concentration Risk [Member] | Revenue Benchmark [Member]        
Number of Major Markets 0 0 0 0
Customer Concentration Risk [Member] | Revenue Benchmark [Member]        
Number of Major Customers 0 0 0 0
Minimum [Member]        
Revenue from Contract with Customer, Sales Returns Policy Term (Day)     14 days  
Revenue from Contract with Customers, Historical Sales Returns, Percent     1.00%  
Maximum [Member]        
Revenue from Contract with Customer, Sales Returns Policy Term (Day)     1 year  
Revenue from Contract with Customers, Historical Sales Returns, Percent     10.00%