Note 7 - Stock-based Compensation - Stock Option Activity (Details) - USD ($)	6 Months Ended	12 Months Ended
	Jun. 30, 2023	Dec. 31, 2022
Stock Option Plan 2013 [Member]
Options outstanding, Shares (in shares)	189,917
Options outstanding, Weighted average exercise price (in dollars per share)	$ 21.14
Options exercised, Shares (in shares)	(17,800)
Options exercised, Weighted average exercise price (in dollars per share)	$ 18.14
Options outstanding, Shares (in shares)	172,117	189,917
Options outstanding, Weighted average exercise price (in dollars per share)	$ 21.45	$ 21.14
Options outstanding, Weighted average remaining contractual term in years (Year)	3 years 6 months
Options outstanding, Intrinsic value	$ 2,450,946
Options exercisable, Shares (in shares)	142,267
Options exercisable, Weighted average exercise price (in dollars per share)	$ 21.41
Options exercisable, weighted average remaining contractual term (Year)	3 years 3 months 18 days
Options exercisable, Intrinsic value	$ 2,031,573
Expected to vest, Shares (in shares)	26,187
Expected to vest, Weighted average exercise price (in dollars per share)	$ 21.66
Expected to vest, Weighted average remaining contractual term in years (Year)	4 years 3 months 18 days
Expected to vest, Intrinsic value	$ 367,458
Options outstanding, Shares (in shares)	172,117	189,917
Options outstanding, Weighted average exercise price (in dollars per share)	$ 21.45	$ 21.14
Stock Option Plan 2022 [Member]
Options outstanding, Shares (in shares)	117,200
Options outstanding, Weighted average exercise price (in dollars per share)	$ 31.00
Options outstanding, Weighted average remaining contractual term in years (Year)		8 years 9 months 21 days
Options outstanding, Intrinsic value	$ 549,668
Options exercisable, Shares (in shares)	0
Options exercisable, Weighted average exercise price (in dollars per share)	$ 0
Options exercisable, Intrinsic value	$ 0
Expected to vest, Shares (in shares)	117,200
Expected to vest, Weighted average exercise price (in dollars per share)	$ 31.00
Expected to vest, Weighted average remaining contractual term in years (Year)	8 years 9 months 21 days
Expected to vest, Intrinsic value	$ 549,668
Options outstanding, Shares (in shares)	117,200
Options outstanding, Weighted average exercise price (in dollars per share)	$ 31.00