Stock Option Plan (Tables)

12 Months Ended

Dec. 31, 2023

Share-Based Payment Arrangement [Abstract]

Stock Options Issued

	Directors						Officers
Grant date	May 12, 2023		May 13, 2022		May 7, 2021		May 12, 2023		May 13, 2022		May 7, 2021
Exercise price	$	33.79	$	47.90	$	43.89	$	33.79	$	47.90	$	43.89
Fair value per option	$	6.53	$	8.34	$	6.32	$	6.06	$	7.66	$	5.96
Volatility	0.319		0.300		0.297		0.288		0.271		0.275
Expected life (years)	5.0		5.0		5.0		7.0		7.0		7.0
Assumed yield	4.94%		4.90%		4.96%		4.96%		4.93%		4.97%
Risk-free rate	3.45%		2.89%		0.77%		3.45%		2.95%		1.24%

Summary of Option Activity

The table below summarizes the option activity for the years 2023, 2022, and 2021:

	2023			2022			2021
	Shares	Weighted Average Exercise Price		Shares	Weighted Average Exercise Price		Shares	Weighted Average Exercise Price
Outstanding at January 1	1,768,375	$	51.28	1,601,250	$	51.73	1,502,670	$	52.86
Granted	253,500	33.79		248,000	47.90		250,500	43.89
Exercised	—	—		(26,875)	44.44		(64,920)	45.07
Expired/Forfeited	(201,875)	46.20		(54,000)	52.60		(87,000)	53.60
Outstanding December 31	1,820,000	49.41		1,768,375	51.28		1,601,250	51.73
Exercisable at December 31	1,177,375	52.52		1,237,250	52.76		1,098,500	53.22