Net Income Per Common Share - Basic and Diluted Net Income Per Common Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Earnings Per Share Reconciliation [Abstract]
Income available to common stockholders	$ 55,352	$ 38,750	$ 135,974	$ 129,462
Income available to common stockholders plus assumed exercises of stock options	$ 55,352	$ 38,750	$ 135,974	$ 129,462
Income available to common stockholders - Shares	32,825,931	32,744,104	32,748,116	32,760,015
Dilutive effect of stock options - Shares	710,627	523,851	681,045	598,822
Income available to common stockholders plus assumed exercises of stock options - Shares	33,536,558	33,267,955	33,429,161	33,358,837
Income available to common stockholders - Per Share Amount	$ 1.69	$ 1.18	$ 4.15	$ 3.95
Income available to common stockholders plus assumed exercises of stock options - Per Share Amount	$ 1.65	$ 1.16	$ 4.07	$ 3.88