Note 8 - Stock Compensation - Summary of the Status of the Stock Option Plan (Details) - $ / shares	3 Months Ended	12 Months Ended
	Mar. 31, 2022	Dec. 31, 2021
Balance, vested (in shares)	34,200	25,300
Balance, weighted average exercise price per share (in dollars per share)	$ 28.43	$ 28.40
Balance, non-vested shares (in shares)	10,800	19,700
Balance, weighted average exercise price per share, non-vested (in dollars per share)	$ 28.86	$ 28.71
Balance (in shares)	45,000	45,000
Balance, weighted average exercise price (in dollars per share)	$ 28.54	$ 28.54
Granted, non-vested shares (in shares)	0
Granted, weighted average exercise price per share, non-vested (in dollars per share)	$ 0
Forfeited, non-vested shares (in shares)	0	0
Forfeited, weighted average exercise price per share, non-vested (in dollars per share)	$ 0	$ 0
Vested, vested (in shares)	8,400	8,900
Vested, weighted average exercise price per share (in dollars per share)	$ 28.42	$ 28.52
Vested, non-vested shares (in shares)	(8,400)	(8,900)
Vested, weighted average exercise price per share, non-vested (in dollars per share)	$ 28.42	$ 28.52
Balance, vested (in shares)	42,600	34,200
Balance, weighted average exercise price per share (in dollars per share)	$ 28.43	$ 28.43
Balance, non-vested shares (in shares)	2,400	10,800
Balance, weighted average exercise price per share, non-vested (in dollars per share)	$ 30.40	$ 28.86
Balance (in shares)	45,000	45,000
Balance, weighted average exercise price (in dollars per share)	$ 28.54	$ 28.54
Remaining contractual life (years), vested (Year)	1 year 2 months 12 days	1 year 2 months 12 days
Remaining contractual life (years), non-vested shares (Year)	2 years 3 months 18 days	1 year 4 months 24 days
Remaining contractual life (years), outstanding shares (Year)	1 year 3 months 18 days	1 year 3 months 18 days
Options exercisable at year end, weighted average exercise price per share, vested (in dollars per share)		$ 0