Stock Option Plan - Stock Options Issued (Detail)	12 Months Ended
	Dec. 31, 2023 $ / shares	Dec. 31, 2022 $ / shares	Dec. 31, 2021 $ / shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise price (in usd per share)	$ 0	$ 44.44	$ 45.07
Directors | May, 13 2022
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise price (in usd per share)	33.79
Fair value per option (in usd per share)	$ 6.53
Volatility	0.319
Expected life (years)	5 years
Assumed yield	4.94%
Risk-free rate	3.45%
Directors | May 7, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise price (in usd per share)	$ 47.90
Fair value per option (in usd per share)	$ 8.34
Volatility	0.300
Expected life (years)	5 years
Assumed yield	4.90%
Risk-free rate	2.89%
Directors | April 24, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise price (in usd per share)	$ 43.89
Fair value per option (in usd per share)	$ 6.32
Volatility	0.297
Expected life (years)	5 years
Assumed yield	4.96%
Risk-free rate	0.77%
Officers | May, 13 2022
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise price (in usd per share)	$ 33.79
Fair value per option (in usd per share)	$ 6.06
Volatility	0.288
Expected life (years)	7 years
Assumed yield	4.96%
Risk-free rate	3.45%
Officers | May 7, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise price (in usd per share)	$ 47.90
Fair value per option (in usd per share)	$ 7.66
Volatility	0.271
Expected life (years)	7 years
Assumed yield	4.93%
Risk-free rate	2.95%
Officers | April 24, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise price (in usd per share)	$ 43.89
Fair value per option (in usd per share)	$ 5.96
Volatility	0.275
Expected life (years)	7 years
Assumed yield	4.97%
Risk-free rate	1.24%