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

3 Months Ended

Mar. 31, 2020

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Assumptions Used in Option Pricing Model

For the Three Months Ended March 31,	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

	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		(8,275	)		25.38
Forfeited		—			—
Outstanding at March 31, 2019		111,500		$	36.51		3.08	$	270
Exercisable at March 31, 2019		37,350		$	29.96		1.48	$	270