Investments - Summary of Marketable Securities (Details) - USD ($) $ in Thousands	Jul. 31, 2024	Jan. 31, 2024
Marketable Securities [Line Items]
Amortized Cost	$ 5,978,372	$ 5,403,503
Gross Unrealized Gains	8,489	11,446
Gross Unrealized Losses	(6,286)	(10,716)
Estimated Fair Value	5,980,575	5,404,233
Commercial paper
Marketable Securities [Line Items]
Amortized Cost	19,636	41,564
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Estimated Fair Value	19,636	41,564
Agency bonds
Marketable Securities [Line Items]
Amortized Cost	1,770,254	1,667,601
Gross Unrealized Gains	1,049	2,426
Gross Unrealized Losses	(2,591)	(3,344)
Estimated Fair Value	1,768,712	1,666,683
Corporate and other debt securities
Marketable Securities [Line Items]
Amortized Cost	711,321	663,122
Gross Unrealized Gains	1,434	1,161
Gross Unrealized Losses	(532)	(1,124)
Estimated Fair Value	712,223	663,159
U.S. government agency securities
Marketable Securities [Line Items]
Amortized Cost	3,356,712	3,003,224
Gross Unrealized Gains	5,993	7,859
Gross Unrealized Losses	(3,146)	(6,241)
Estimated Fair Value	3,359,559	3,004,842
Treasury bills
Marketable Securities [Line Items]
Amortized Cost	120,449	27,992
Gross Unrealized Gains	13	0
Gross Unrealized Losses	(17)	(7)
Estimated Fair Value	$ 120,445	$ 27,985