Net Income per Common Share - Reconciliation between basic and diluted net income per share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 31, 2023	Oct. 31, 2022	Oct. 31, 2023	Oct. 31, 2022
Net Income per Common Share
Net Income (Loss)	$ 127,640	$ 61,103	$ 147,314	$ 128,056
Basic net income (loss) per share:
Basic common shares	45,723	47,488	45,904	47,832
Basic net income (loss) per share (in dollars per share)	$ 2.79	$ 1.29	$ 3.21	$ 2.68
Diluted net income (loss) per share:
Basic common shares	45,723	47,488	45,904	47,832
Diluted restricted stock awards and stock options	837	987	1,088	1,034
Diluted common shares	46,560	48,475	46,992	48,866
Diluted net income (loss) per share (in dollars per share)	$ 2.74	$ 1.26	$ 3.13	$ 2.62