Investments - Schedule of Marketable Securities (Details) - USD ($) $ in Thousands	Apr. 30, 2024	Jan. 31, 2024
Marketable Securities [Line Items]
Amortized Cost	$ 5,512,253	$ 5,403,503
Gross Unrealized Gains	132	11,446
Gross Unrealized Losses	(23,648)	(10,716)
Estimated Fair Value	5,488,737	5,404,233
Commercial paper
Marketable Securities [Line Items]
Amortized Cost	19,737	41,564
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Estimated Fair Value	19,737	41,564
Agency bonds
Marketable Securities [Line Items]
Amortized Cost	1,752,707	1,667,601
Gross Unrealized Gains	24	2,426
Gross Unrealized Losses	(6,482)	(3,344)
Estimated Fair Value	1,746,249	1,666,683
Corporate and other debt securities
Marketable Securities [Line Items]
Amortized Cost	652,318	663,122
Gross Unrealized Gains	104	1,161
Gross Unrealized Losses	(2,633)	(1,124)
Estimated Fair Value	649,789	663,159
U.S. government agency securities
Marketable Securities [Line Items]
Amortized Cost	3,032,764	3,003,224
Gross Unrealized Gains	4	7,859
Gross Unrealized Losses	(14,488)	(6,241)
Estimated Fair Value	3,018,280	3,004,842
Treasury bills
Marketable Securities [Line Items]
Amortized Cost	54,727	27,992
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(45)	(7)
Estimated Fair Value	$ 54,682	$ 27,985