Note 7 - Stock-based Compensation - Summary of Stock Option Activity (Details) - USD ($)	3 Months Ended		12 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022	Dec. 31, 2021
Outstanding (in shares)	95,000	67,000	67,000
Outstanding, grant date weighted-average exercise price (in dollars per share)	$ 2.76	$ 2.72	$ 2.72
Outstanding, weighted average remaining contractual life (Year)		3 years 1 month 2 days	4 years 9 months 29 days	3 years 3 months 29 days
Granted (in shares)	50,000
Granted (in dollars per share)	$ 2.93
Granted (Year)	7 years
Forfeited (in shares)	(2,000)
Forfeited (in dollars per share)	$ 3.90
Outstanding, intrinsic value		$ 4,000		$ 0
Exercisable (in shares)	48,000	59,000
Exercisable, grant date weighted-average exercise price (in dollars per share)	$ 2.73	$ 2.72
Exercisable, weighted average remaining contractual life (Year)		2 years 9 months 7 days
Outstanding (in shares)	143,000	67,000	95,000	67,000
Outstanding, grant date weighted-average exercise price (in dollars per share)	$ 2.80	$ 2.72	$ 2.76	$ 2.72
Minimum [Member]
Outstanding, weighted average remaining contractual life (Year)	4 years 9 months 3 days
Exercisable, weighted average remaining contractual life (Year)	2 years 6 months 3 days
Maximum [Member]
Outstanding, intrinsic value	$ 26,000