Schedule Of Computation of Earnings Per Share - Summary of Calculation of Basic Earnings Per Common Share and Diluted Earnings Per Common Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2024	Jun. 30, 2024	Mar. 31, 2024	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Sep. 30, 2024	Sep. 30, 2023
Numerator:
Net Income (Loss)	$ 92,748	$ 102,519	$ 90,695	$ 98,213	$ 91,319	$ 76,097	$ 285,962	$ 265,629
Denominator:
Denominator for basic earnings per share-weighted average common shares	26,695			26,644			26,686	26,626
Dilutive effect of share-based awards	94			135			99	129
Denominator for diluted earnings per share-adjusted weighted average common shares	26,789			26,779			26,785	26,755
Basic Earnings Per Share	$ 3.47			$ 3.69			$ 10.72	$ 9.98
Diluted Earnings Per Share	$ 3.46			$ 3.67			$ 10.68	$ 9.93