Calculation of Earnings Per Share - Calculation of Basic and Diluted Earnings Per Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Earnings Per Share [Abstract]
Income (Loss) from Continuing Operations, Per Basic Share	$ 2.05	$ 2.09
Calculation of Basic Earnings Per Share:
Net Income	$ 36,344	$ 36,933
Weighted shares outstanding (shares)	17,759,896	17,678,060
Basic Earnings Per Share (in dollars per share)	$ 2.05	$ 2.09
Reconciliation of Numerator:
Net Income	$ 36,344	$ 36,933
Reconciliation of Denominator:
Weighted shares outstanding - Basic (shares)	17,759,896	17,678,060
Effect of dilutive securities:
Share-based compensation (shares)	71,876	83,059
Adjusted denominator-Diluted (shares)	17,831,772	17,761,119
Income (Loss) from Continuing Operations, Per Diluted Share	$ 2.04	$ 2.08
Diluted Earnings Per Share (in dollars per share)	$ 2.04	$ 2.08
Net Income	$ 36,344	$ 36,933
Basic (shares)	17,759,896	17,678,060
Income (Loss) from Continuing Operations, Per Basic Share	$ 2.05	$ 2.09
Basic (in dollars per share)	$ 2.05	$ 2.09
Share-based compensation (shares)	71,876	83,059
Diluted (shares)	17,831,772	17,761,119
Income (Loss) from Continuing Operations, Per Diluted Share	$ 2.04	$ 2.08
Diluted (in dollars per share)	$ 2.04	$ 2.08
Retained Earnings [Member]
Earnings Per Share [Abstract]
Income (Loss) from Continuing Operations, Net of Tax, Attributable to Parent	$ 36,344	$ 36,933
Calculation of Basic Earnings Per Share:
Net Income	36,344	36,933
Reconciliation of Numerator:
Net Income	36,344	36,933
Income (Loss) from Continuing Operations, Net of Tax, Attributable to Parent	36,344	36,933
Net Income	$ 36,344	$ 36,933