Note 2 - Summary of Significant Accounting Policies (Details Textual)		3 Months Ended	9 Months Ended
	Aug. 30, 2019 USD ($)	Sep. 30, 2019 USD ($)	Sep. 30, 2019 USD ($) shares	Sep. 30, 2018 shares	Jan. 01, 2019 USD ($)	Dec. 31, 2018 USD ($)
Operating Lease, Right-of-Use Asset		$ 887,000	$ 887,000
Contract with Customer, Liability, Revenue Recognized		50,000	480,000
Contract with Customer, Liability, Current		840,000	$ 840,000			$ 485,000
Number of Reportable Segments			2
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount | shares			7,720,082	6,175,520
Operating Lease, Liability, Total		$ 904,000	$ 904,000
Warrant [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount | shares			324,444
Supply Agreement [Member]
Supply Agreement, Term	5 years
Supply Agreement, Renewal Term	2 years
Contract with Customer, Liability, Total	$ 2,000,000
Accounting Standards Update 2016-02 [Member]
Operating Lease, Right-of-Use Asset					$ 966,000
Operating Lease, Liability, Total					$ 966,000