Note 10 - Stock Plans - Non-vested Restricted Stock (Details) - Restricted Stock [Member] - $ / shares	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Non-vested balance (in shares)	73,719	62,486
Outstanding, weighted average grant date fair value (in dollars per share)	$ 50.03	$ 51.46
Granted (in shares)	22,479	36,734
Granted, weighted average grant date fair value (in dollars per share)	$ 46.96	$ 49.28
Forfeited (in shares)	(1,705)	(1,020)
Forfeited, weighted average grant date fair value (in dollars per share)	$ 48.45	$ 50.06
Vested (in shares)	(25,868)	(24,481)
Vested, weighted average grant date fair value (in dollars per share)	$ 51.03	$ 52.57
Non-vested balance (in shares)	68,625	73,719
Outstanding, weighted average grant date fair value (in dollars per share)	$ 48.68	$ 50.03
The 2012 Director Stock Incentive Plan [Member]
Non-vested balance (in shares)	12,519	23,872
Granted (in shares)	0	0
Forfeited (in shares)	0	0
Vested (in shares)	(7,719)	(11,353)
Non-vested balance (in shares)	4,800	12,519
The 2012 Omnibus Stock Incentive Plan [Member]
Non-vested balance (in shares)	61,200	38,614
Granted (in shares)	22,479	36,734
Forfeited (in shares)	(1,705)	(1,020)
Vested (in shares)	(18,149)	(13,128)
Non-vested balance (in shares)	63,825	61,200