Investments - Summary of Marketable Securities (Details) - USD ($) $ in Thousands	Oct. 31, 2024	Jan. 31, 2024
Marketable Securities [Line Items]
Amortized Cost	$ 6,420,007	$ 5,403,503
Gross Unrealized Gains	15,304	11,446
Gross Unrealized Losses	(7,097)	(10,716)
Estimated Fair Value	6,428,214	5,404,233
Commercial paper
Marketable Securities [Line Items]
Amortized Cost	18,707	41,564
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Estimated Fair Value	18,707	41,564
Agency bonds
Marketable Securities [Line Items]
Amortized Cost	1,413,493	1,667,601
Gross Unrealized Gains	2,199	2,426
Gross Unrealized Losses	(844)	(3,344)
Estimated Fair Value	1,414,848	1,666,683
Corporate and other debt securities
Marketable Securities [Line Items]
Amortized Cost	719,929	663,122
Gross Unrealized Gains	2,505	1,161
Gross Unrealized Losses	(433)	(1,124)
Estimated Fair Value	722,001	663,159
U.S. government agency securities
Marketable Securities [Line Items]
Amortized Cost	4,099,278	3,003,224
Gross Unrealized Gains	10,580	7,859
Gross Unrealized Losses	(5,805)	(6,241)
Estimated Fair Value	4,104,053	3,004,842
Treasury bills
Marketable Securities [Line Items]
Amortized Cost	168,600	27,992
Gross Unrealized Gains	20	0
Gross Unrealized Losses	(15)	(7)
Estimated Fair Value	$ 168,605	$ 27,985