Note 3 - Summary of Significant Accounting Policies (Details Textual) - USD ($)		3 Months Ended
	Aug. 30, 2019	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Contract with Customer, Liability, Revenue Recognized		$ 273,000
Contract with Customer, Liability, Current		696,000		$ 608,000
Contract with Customer, Liability, Noncurrent		1,520,000		$ 1,596,000
Exclusivity Fee [Member]
Contract with Customer, Liability, Revenue Recognized		71,000	$ 71,000
Contract with Customer, Liability, Current		286,000
Contract with Customer, Liability, Noncurrent		1,262,000
Contract with Customer, Liability, Total		1,548,000
Supply Agreement [Member]
Supply Agreement, Term (Year)	5 years
Supply Agreement, Renewal Term (Year)	2 years
Contract with Customer, Liability, Total	$ 2,000,000
Proceeds from Customers		$ 2,000,000