Note 2 - Summary of Significant Accounting Policies (Details Textual)	3 Months Ended	6 Months Ended
	Jun. 30, 2019 USD ($)	Jun. 30, 2019 USD ($) shares	Jun. 30, 2018 shares	Jan. 01, 2019 USD ($)	Dec. 31, 2018 USD ($)
Operating Lease, Right-of-Use Asset	$ 915,000	$ 915,000
Contract with Customer, Liability, Revenue Recognized	83,000	446,000
Contract with Customer, Liability, Current	577,000	$ 577,000			$ 485,000
Number of Reportable Segments		2
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount | shares		7,051,813	2,817,677
Operating Lease, Liability, Total	$ 928,000	$ 928,000
Warrant [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount | shares		540,945
Accounting Standards Update 2016-02 [Member]
Operating Lease, Right-of-Use Asset				$ 966,000
Operating Lease, Liability, Total				$ 966,000