Investments - Summary of Marketable Securities (Details) - USD ($) $ in Thousands	Jan. 31, 2025	Jan. 31, 2024
Marketable Securities [Line Items]
Amortized Cost	$ 6,436,471	$ 5,403,503
Gross Unrealized Gains	12,170	11,446
Gross Unrealized Losses	(6,312)	(10,716)
Estimated Fair Value	6,442,329	5,404,233
Commercial paper
Marketable Securities [Line Items]
Amortized Cost	20,841	41,564
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Estimated Fair Value	20,841	41,564
Agency bonds
Marketable Securities [Line Items]
Amortized Cost	1,173,518	1,667,601
Gross Unrealized Gains	1,609	2,426
Gross Unrealized Losses	(643)	(3,344)
Estimated Fair Value	1,174,484	1,666,683
Corporate and other debt securities
Marketable Securities [Line Items]
Amortized Cost	719,145	663,122
Gross Unrealized Gains	2,069	1,161
Gross Unrealized Losses	(419)	(1,124)
Estimated Fair Value	720,795	663,159
U.S. government agency securities
Marketable Securities [Line Items]
Amortized Cost	4,412,730	3,003,224
Gross Unrealized Gains	8,449	7,859
Gross Unrealized Losses	(5,249)	(6,241)
Estimated Fair Value	4,415,930	3,004,842
Treasury bills
Marketable Securities [Line Items]
Amortized Cost	110,237	27,992
Gross Unrealized Gains	43	0
Gross Unrealized Losses	(1)	(7)
Estimated Fair Value	$ 110,279	$ 27,985