Stock Option Plans (Tables)

12 Months Ended

Dec. 31, 2018

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Stock Option Activity

	2018			2017
Options outstanding  at the
beginning of the year		1,289,080			1,088,278
Options granted		232,200			313,900
Options forfeited		(11,500	)		(4,000	)
Options exercised		(75,500	)		(109,098	)
Options outstanding at
the end of the year		1,434,280			1,289,080
Options exercisable at the
end of the year		918,405			814,180
Common stock available for future grants at the end of the year		85,000			62,700
Weighted average exercise price per share:
Granted	$	22.75		$	24.87
Forfeited		23.07			19.12
Exercised		11.47			13.13
Outstanding		18.07			16.87
Exercisable		15.15			13.38

Summary of Options Outstanding

	Options Outstanding					Options Exercisable
Range of Exercise Prices		Number Outstanding	Weighted-Average Remaining Contractual Life (Years)		Weighted-Average Exercise Price	Number Exercisable		Weighted-Average Exercise Price
$7.30 to $10.74		299,180	3	$	9.88	299,180	$	9.88
$10.75 to $16.82		262,750	4		13.62	262,750		13.62
$16.83 to $22.08		337,875	7		19.41	244,625		18.75
$22.09 to $23.97		228,200	10		22.79	20,000		22.66
$23.98 to $28.20		306,275	9		24.87	91,850		25.41
		1,434,280				918,405

Assumptions Used to Value Option Grants

	2018		2017
Expected life in years		5		5
Interest rate		2.43 - 3.02%		1.82 - 1.95%
Volatility		.287 - .316		.259 - .277
Dividend yield		1.8 - 2.75%		1.5 - 1.6%