Note 7 - Stock Plans - Summary of Weighted Average Fair Value and Vesting of Restricted Stock Grants (Details) - Restricted Stock [Member] - $ / shares		6 Months Ended
		Jun. 30, 2024		Jun. 30, 2023
Granted, awards (in shares)		22,479		36,734
Granted, weighted average grant date fair value (in dollars per share)		$ 46.96		$ 49.28
The 2012 Omnibus Stock Incentive Plan [Member] | Award Date One [Member]
Granted, awards (in shares)	[1]	10,000		18,000
Granted, weighted average grant date fair value (in dollars per share)		$ 46.96		$ 49.43
The 2012 Omnibus Stock Incentive Plan [Member] | Award Date Two [Member]
Granted, awards (in shares)		1,558	[1]	17,684	[2]
Granted, weighted average grant date fair value (in dollars per share)		$ 46.96		$ 49.43
The 2012 Omnibus Stock Incentive Plan [Member] | Award Date Three [Member]
Granted, awards (in shares)		10,871	[2]	50	[3]
Granted, weighted average grant date fair value (in dollars per share)		$ 46.96		$ 49.43
The 2012 Omnibus Stock Incentive Plan [Member] | Award Date Four [Member]
Granted, awards (in shares)		50	[3]	1,000
Granted, weighted average grant date fair value (in dollars per share)		$ 46.96		$ 44.06

[1] Vest after 3 years – 33% each year

[2] Vest fully after 3 years

[3] Vest after 1 year