CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 31, 2021	Jul. 31, 2020	Jul. 31, 2021	Jul. 31, 2020
Statement of Comprehensive Income [Abstract]
Net income	$ 317,084	$ 185,989	$ 544,615	$ 213,064
Other comprehensive (loss) income:
Unrealized (loss) gain on available-for-sale marketable securities, net of tax	(53)	885	(692)	1,963
Comprehensive income	$ 317,031	$ 186,874	$ 543,923	$ 215,027