Note 1. Nature of Business and Significant Accounting Policies - Option Pricing Model Valuation Assumptions (Details) - $ / shares	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Expected life of option grants (Year)	10 years
Weighted-average grant date fair value (in dollars per share)	$ 16.36	$ 13.97	$ 10.85
Employee Stock Option [Member]
Dividend yield	0.45%		0.55%
Expected volatility	22.31%		23.57%
Risk-free interest rate	4.22%		1.62%
Expected life of option grants (Year)	6 years 3 months	6 years 3 months	6 years 3 months
Weighted-average grant date fair value (in dollars per share)	$ 16.36		$ 10.85
Employee Stock Option [Member] | Minimum
Dividend yield		0.43%
Expected volatility		22.65%
Risk-free interest rate		1.87%
Weighted-average grant date fair value (in dollars per share)		$ 13.94
Employee Stock Option [Member] | Maximum
Dividend yield		0.45%
Expected volatility		23.52%
Risk-free interest rate		3.12%
Weighted-average grant date fair value (in dollars per share)		$ 15.09
Stock Purchase Grants [Member]
Weighted-average grant date fair value (in dollars per share)	$ 8.35	$ 7.88	$ 7.67
Stock Purchase Grants [Member] | Minimum
Dividend yield	0.48%	0.43%	0.49%
Expected volatility	15.86%	17.97%	37.51%
Risk-free interest rate	4.67%	0.14%	0.00%
Expected life of option grants (Year)	3 years	3 months	3 months
Stock Purchase Grants [Member] | Maximum
Dividend yield	0.58%	0.44%	0.61%
Expected volatility	29.69%	21.16%	38.65%
Risk-free interest rate	5.47%	2.24%	0.06%
Expected life of option grants (Year)	6 months	6 months	6 months