Note 3 - Stock-based Compensation and Shareholders' Equity (Tables)

9 Months Ended

Sep. 30, 2020

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Assumptions Used in Option Pricing Model

For the Nine Months Ended September 30,	2020			2019
Risk free interest rate		1.52	%		2.52	%
Dividend yield		3.60	%		3.36	%
Volatility		13.46	%		16.44	%
Expected life (years)		4.03			4.17

Stock Option Activity

Stock option activity during the nine months ended September 30, 2020 and 2019 is as follows:

	Number of options			Weighted average exercise price		Weighted average remaining contractual term (in years)		Aggregate intrinsic value
Outstanding at December 31, 2019		103,350		$	36.96
Granted		25,000			36.50
Exercised		(9,550	)		29.39
Forfeited		—			—
Outstanding at September 30, 2020		118,800		$	37.47		2.46	$	-
Exercisable at September 30, 2020		44,600		$	34.27		0.92	$	-

	Number of options			Weighted average exercise price		Weighted average remaining contractual term (in years)		Aggregate intrinsic value
Outstanding at December 31, 2018		95,075		$	35.11
Granted		24,700			38.15
Exercised		(8,775	)		25.64
Forfeited		(1,500	)		37.20
Outstanding at September 30, 2019		109,500		$	36.53		2.34	$	357
Exercisable at September 30, 2019		36,350		$	29.95		0.72	$	318