Cash Equivalents and Investments - Schedule of Cash Equivalents and Short-term Investments (Details) - USD ($) $ in Thousands	Jan. 31, 2022	Jan. 31, 2021
Cash and Cash Equivalents [Line Items]
Amortized Cost	$ 2,405,617	$ 2,430,865
Unrealized Gain	10	2,000
Unrealized Loss	(11,747)	(24)
Estimated Fair Value	2,393,880	2,432,841
Cash and cash equivalents
Cash and Cash Equivalents [Line Items]
Amortized Cost	152,223	311,257
Unrealized Gain	0	0
Unrealized Loss	0	0
Estimated Fair Value	152,223	311,257
Cash and cash equivalents | Money market funds
Cash and Cash Equivalents [Line Items]
Amortized Cost	152,223	311,257
Unrealized Gain	0	0
Unrealized Loss	0	0
Estimated Fair Value	152,223	311,257
Short-term Investments
Cash and Cash Equivalents [Line Items]
Amortized Cost	2,253,394	2,119,608
Unrealized Gain	10	2,000
Unrealized Loss	(11,747)	(24)
Estimated Fair Value	2,241,657	2,121,584
Short-term Investments | U.S. treasury securities
Cash and Cash Equivalents [Line Items]
Amortized Cost	1,922,344	1,888,882
Unrealized Gain	10	1,571
Unrealized Loss	(10,166)	(22)
Estimated Fair Value	1,912,188	1,890,431
Short-term Investments | Corporate debt securities
Cash and Cash Equivalents [Line Items]
Amortized Cost	331,050	230,726
Unrealized Gain	0	429
Unrealized Loss	(1,581)	(2)
Estimated Fair Value	$ 329,469	$ 231,153