CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 31, 2021	Oct. 31, 2020	Oct. 31, 2021	Oct. 31, 2020
Statement of Comprehensive Income [Abstract]
Net income	$ 340,383	$ 198,642	$ 884,998	$ 411,706
Other comprehensive (loss) income:
Unrealized (loss) gain on available-for-sale marketable securities, net of tax	(5,275)	(1,455)	(5,967)	508
Comprehensive income	$ 335,108	$ 197,187	$ 879,031	$ 412,214