Cash Equivalents and Investments - Schedule of Cash and Cash Equivalents and Investments Fair Value (Details) - USD ($) $ in Thousands	Apr. 30, 2022	Jan. 31, 2022
Cash equivalents:
Amortized Cost	$ 857,328	$ 845,234
Gross Unrealized Gains	1	1
Gross Unrealized Losses	(16)	(5)
Estimated Fair Value	857,313	845,230
Investments:
Amortized Cost	4,007,742	4,037,943
Gross Unrealized Gains	190	204
Gross Unrealized Losses	(43,875)	(15,576)
Estimated Fair Value	3,964,057	4,022,571
Amortized Cost	4,865,070	4,883,177
Gross Unrealized Gains	191	205
Gross Unrealized Losses	(43,891)	(15,581)
Estimated Fair Value	4,821,370	4,867,801
Commercial paper
Investments:
Amortized Cost	776,878	884,376
Gross Unrealized Gains	0	81
Gross Unrealized Losses	(3,255)	(821)
Estimated Fair Value	773,623	883,636
Corporate notes and bonds
Investments:
Amortized Cost	2,481,897	2,610,010
Gross Unrealized Gains	23	91
Gross Unrealized Losses	(31,188)	(12,062)
Estimated Fair Value	2,450,732	2,598,039
U.S. government and agency securities
Investments:
Amortized Cost	597,500	439,449
Gross Unrealized Gains	125	28
Gross Unrealized Losses	(8,990)	(2,558)
Estimated Fair Value	588,635	436,919
Certificates of deposit
Investments:
Amortized Cost	151,467	104,108
Gross Unrealized Gains	42	4
Gross Unrealized Losses	(442)	(135)
Estimated Fair Value	151,067	103,977
Money market funds
Cash equivalents:
Amortized Cost	744,931	722,492
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Estimated Fair Value	744,931	722,492
Commercial paper
Cash equivalents:
Amortized Cost	98,852	77,795
Gross Unrealized Gains	1	1
Gross Unrealized Losses	(14)	(2)
Estimated Fair Value	98,839	77,794
U.S. government and agency securities
Cash equivalents:
Amortized Cost		36,997
Gross Unrealized Gains		0
Gross Unrealized Losses		(2)
Estimated Fair Value		36,995
Corporate notes and bonds
Cash equivalents:
Amortized Cost	13,545	7,950
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(2)	(1)
Estimated Fair Value	$ 13,543	$ 7,949