Note 16 - Income Taxes (Details Textual) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Income (Loss) from Continuing Operations before Income Taxes, Domestic	$ (11,850,000)	$ (16,728,000)
Income (Loss) from Continuing Operations before Income Taxes, Foreign	(30,000)	(83,000)
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount	(72,000)	$ 197,000
Domestic Tax Authority [Member]
Operating Loss Carryforwards, Total	125,077,000
Operating Loss Carryforwards, Subject to Expiration	101,805,000
Operating Loss Carryforwards, Not Subject to Expiration	23,272,000
Domestic Tax Authority [Member] | Research Tax Credit Carryforward [Member]
Tax Credit Carryforward, Amount	1,521,000
State and Local Jurisdiction [Member]
Operating Loss Carryforwards, Total	60,984,000
State and Local Jurisdiction [Member] | Research Tax Credit Carryforward [Member]
Tax Credit Carryforward, Amount	1,616,000
Foreign Tax Authority [Member]
Operating Loss Carryforwards, Total	$ 629,000