Note 5 - Stock-based Compensation (Details Textual)	3 Months Ended		9 Months Ended
	Sep. 30, 2020 USD ($) shares	Sep. 30, 2019 USD ($)	Sep. 30, 2020 USD ($) shares	Sep. 30, 2019 USD ($)
Number of Stock-based Compensation Plans in Effect	3		3
Share-based Payment Arrangement, Expense | $	$ 207,000	$ 49,000	$ 330,000	$ 129,000
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount, Total | $	$ 235,000		$ 235,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period (in shares)	0		0
Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures and Expirations in Period, Total (in shares)	0
Three Independent Members of the Board of Directors [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Net of Forfeitures, Total (in shares)	4,380
Shares Issued, Value, Share-based Payment Arrangement, after Forfeiture, Total | $	$ 150,000
The 2020 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized (in shares)	200,000		200,000