Note 11 - Stock Based Compensation and Other Plans - Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
The 2008 Plan [Member]
Covered Shares (in shares)	1,457,936	2,227,211
Weighted- Average Exercise Price (in dollars per share)	$ 1.31	$ 1.22
Weighted- Average Remaining Contractual Term (Year)	2 years 7 months 6 days	3 years 7 months 17 days	4 years 9 months 29 days
Aggregate Intrinsic Value	$ 72	$ 113	$ 452
Exercised/cancelled, covered shares (in shares)	87,712	57,500
Exercised/cancelled, weighted-average exercise price (in dollars per share)	$ 1.08	$ 1.00
Forfeited or expired, covered shares (in shares)	679,062	711,775
Forfeited or expired, weighted-average exercise price (in dollars per share)		$ 0
Covered Shares (in shares)	691,162	1,457,936	2,227,211
Weighted- Average Exercise Price (in dollars per share)	$ 1.53	$ 1.31	$ 1.22
Exercisable, covered shares (in shares)	691,162
Exercisable, weighted-average exercise price (in dollars per share)	$ 1.53
Exercisable, weighted average remaining contractual term (Year)	2 years 7 months 6 days
Exercisable, aggregate intrinsic value	$ 72
The 2018 Plan [Member]
Covered Shares (in shares)	430,000	555,000
Weighted- Average Exercise Price (in dollars per share)	$ 0.90	$ 0.89
Weighted- Average Remaining Contractual Term (Year)	6 years 9 months 25 days	7 years 10 months 13 days	8 years 10 months 17 days
Aggregate Intrinsic Value	$ 31	$ 8
Exercised/cancelled, covered shares (in shares)	60,000	18,750
Exercised/cancelled, weighted-average exercise price (in dollars per share)	$ 0.85	$ 1
Forfeited or expired, covered shares (in shares)	210,000	106,250
Covered Shares (in shares)	160,000	430,000	555,000
Weighted- Average Exercise Price (in dollars per share)	$ 0.93	$ 0.90	$ 0.89
Exercisable, covered shares (in shares)	118,750
Exercisable, weighted-average exercise price (in dollars per share)	$ 0.97
Exercisable, weighted average remaining contractual term (Year)	6 years 7 months 6 days
Exercisable, aggregate intrinsic value	$ 31
Inducement Plan [Member]
Covered Shares (in shares)	200,000
Weighted- Average Exercise Price (in dollars per share)	$ 0.85
Weighted- Average Remaining Contractual Term (Year)	8 years 8 months 1 day	9 years 8 months 1 day
Aggregate Intrinsic Value	$ 57	$ 60
Exercised/cancelled, covered shares (in shares)	50,000
Exercised/cancelled, weighted-average exercise price (in dollars per share)	$ 0.85
Covered Shares (in shares)	150,000	200,000
Weighted- Average Exercise Price (in dollars per share)	$ 0.85	$ 0.85
Granted Shares (in shares)		200,000
Granted, weighted-average exercise price (in dollars per share)		$ 0.85
Granted, weighted-average remaining contractual term (Year)		9 years 8 months 1 day
CEO Inducement Plan [Member]
Weighted- Average Remaining Contractual Term (Year)	9 years 1 month 24 days
Covered Shares (in shares)	630,000
Weighted- Average Exercise Price (in dollars per share)	$ 1.90
Exercisable, aggregate intrinsic value	$ 0
Granted Shares (in shares)	630,000
Granted, weighted-average exercise price (in dollars per share)	$ 1.90
Granted, weighted-average remaining contractual term (Year)	9 years 1 month 24 days
The 2020 Plan [Member]
Weighted- Average Remaining Contractual Term (Year)	4 years 1 month 6 days
Forfeited or expired, covered shares (in shares)	180,000
Covered Shares (in shares)	385,000
Weighted- Average Exercise Price (in dollars per share)	$ 1.55
Granted Shares (in shares)	565,000
Granted, weighted-average exercise price (in dollars per share)	$ 1.55
Granted, weighted-average remaining contractual term (Year)		4 years 1 month 6 days