Investments - Schedule of Marketable Securities (Details) - USD ($) $ in Thousands	Oct. 31, 2023	Jan. 31, 2023
Marketable Securities [Line Items]
Amortized Cost	$ 5,037,437	$ 4,392,058
Gross Unrealized Gains	64	599
Gross Unrealized Losses	(35,994)	(66,821)
Estimated Fair Value	5,001,507	4,325,836
Commercial paper
Marketable Securities [Line Items]
Amortized Cost	56,098	77,701
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Estimated Fair Value	56,098	77,701
Agency bonds
Marketable Securities [Line Items]
Amortized Cost	1,608,658	823,027
Gross Unrealized Gains	4	63
Gross Unrealized Losses	(11,879)	(12,440)
Estimated Fair Value	1,596,783	810,650
Corporate and other debt securities
Marketable Securities [Line Items]
Amortized Cost	590,977	555,354
Gross Unrealized Gains	41	385
Gross Unrealized Losses	(4,231)	(4,845)
Estimated Fair Value	586,787	550,894
U.S. government agency securities
Marketable Securities [Line Items]
Amortized Cost	2,731,636	2,910,572
Gross Unrealized Gains	19	150
Gross Unrealized Losses	(19,879)	(49,507)
Estimated Fair Value	2,711,776	2,861,215
Treasury bills
Marketable Securities [Line Items]
Amortized Cost	50,068	25,404
Gross Unrealized Gains	0	1
Gross Unrealized Losses	(5)	(29)
Estimated Fair Value	$ 50,063	$ 25,376