Investments - Summary of Marketable Securities (Details) - USD ($) $ in Thousands	Oct. 31, 2025	Jan. 31, 2025
Marketable Securities [Line Items]
Amortized Cost	$ 6,714,541	$ 6,436,471
Gross Unrealized Gains	14,491	12,170
Gross Unrealized Losses	(1,604)	(6,312)
Estimated Fair Value	6,727,428	6,442,329
U.S. government agency securities
Marketable Securities [Line Items]
Amortized Cost	4,940,717	4,412,730
Gross Unrealized Gains	11,255	8,449
Gross Unrealized Losses	(1,116)	(5,249)
Estimated Fair Value	4,950,856	4,415,930
Agency bonds
Marketable Securities [Line Items]
Amortized Cost	967,640	1,173,518
Gross Unrealized Gains	1,098	1,609
Gross Unrealized Losses	(334)	(643)
Estimated Fair Value	968,404	1,174,484
Corporate and other debt securities
Marketable Securities [Line Items]
Amortized Cost	748,969	719,145
Gross Unrealized Gains	2,110	2,069
Gross Unrealized Losses	(154)	(419)
Estimated Fair Value	750,925	720,795
Treasury bills
Marketable Securities [Line Items]
Amortized Cost	54,219	110,237
Gross Unrealized Gains	28	43
Gross Unrealized Losses	0	(1)
Estimated Fair Value	54,247	110,279
Commercial paper
Marketable Securities [Line Items]
Amortized Cost	2,996	20,841
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Estimated Fair Value	$ 2,996	$ 20,841