Note 3 - Summary of Significant Accounting Policies (Details Textual)	3 Months Ended
	Mar. 31, 2020 USD ($) shares	Mar. 31, 2019 shares	Dec. 31, 2019 USD ($)
Number of Operating Segments	2
Accounts Receivable, Allowance for Credit Loss, Ending Balance	$ 10,000		$ 10,000
Inventory Valuation Reserves, Ending Balance	$ 768,000		$ 768,000
Options and Warrants [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount (in shares) | shares	1,875,886	10,942,963
Minimum [Member]
Property, Plant and Equipment, Useful Life (Year)	2 years
Maximum [Member]
Property, Plant and Equipment, Useful Life (Year)	7 years