Stock Option Plans - Assumptions Used to Value Option Grants (Details)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected life in years	7 years	7 years
Interest rate	4.17%	2.79%
Volatility	0.422%	0.413%
Dividend yield	1.8%	1.9