Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 31, 2021	Jul. 31, 2020	Jul. 31, 2021	Jul. 31, 2020
Income Tax Disclosure [Abstract]
Income before provision for income taxes	$ 323,884	$ 190,185	$ 552,815	$ 219,360
Provision for income taxes	$ 6,800	$ 4,196	$ 8,200	$ 6,296
Effective tax rate	2.10%	2.20%	1.50%	2.90%