Net Income per Common Share - Reconciliation of Weighted Average Common Shares Outstanding Used for Computation of Basic and Diluted Net Income per Common Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 31, 2025	Oct. 31, 2024	Oct. 31, 2025	Oct. 31, 2024
Earnings Per Share [Abstract]
Net Income (Loss)	$ 116,440	$ 102,911	$ 368,652	$ 282,161
Basic weighted-average common shares outstanding	89,706,922	92,270,583	90,360,467	92,819,987
Effect of dilutive options, performance stock units and restricted stock units	1,581,202	1,587,267	1,601,720	1,692,002
Diluted weighted-average shares outstanding	91,288,124	93,857,850	91,962,187	94,511,989
Basic	$ 1.3	$ 1.12	$ 4.08	$ 3.04
Diluted	$ 1.28	$ 1.1	$ 4.01	$ 2.99