Note 2 - Summary of Significant Accounting Policies (Details Textual) - USD ($)		3 Months Ended
	Aug. 30, 2019	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Deferred Revenue, Total		$ 293,000
Deferred Revenue, Current, Total		617,000		$ 620,000
Deferred Revenue, Noncurrent, Total		$ 1,814,000		$ 1,901,000
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount (in shares)		6,831,100	7,055,832
Warrant [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount (in shares)		224,445	246,500
Exclusivity Fee [Member]
Deferred Revenue, Total		$ 1,834,000
Deferred Revenue, Current, Total		286,000
Deferred Revenue, Noncurrent, Total		1,548,000
Contract with Customer, Liability, Revenue Recognized		$ 71,000
Supply Agreement [Member]
Supply Agreement, Term (Year)	5 years	7 years
Supply Agreement, Renewal Term (Year)	2 years	2 years
Contract with Customer, Liability, Total	$ 2,000,000
Proceeds from Customers		$ 2,000,000