Investments - Summary of Marketable Securities (Details) - USD ($) $ in Thousands	Jul. 31, 2022	Jan. 31, 2022
Marketable Securities [Line Items]
Amortized Cost	$ 4,646,483	$ 4,380,350
Gross Unrealized Gains	590	35
Gross Unrealized Losses	(64,365)	(23,939)
Estimated Fair Value	4,582,708	4,356,446
Commercial paper
Marketable Securities [Line Items]
Amortized Cost	64,596	28,723
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Estimated Fair Value	64,596	28,723
Agency bonds
Marketable Securities [Line Items]
Amortized Cost	654,632	632,935
Gross Unrealized Gains	165	2
Gross Unrealized Losses	(10,965)	(3,328)
Estimated Fair Value	643,832	629,609
Corporate and other debt securities
Marketable Securities [Line Items]
Amortized Cost	411,999	282,124
Gross Unrealized Gains	81	5
Gross Unrealized Losses	(3,615)	(1,202)
Estimated Fair Value	408,465	280,927
U.S. government agency securities
Marketable Securities [Line Items]
Amortized Cost	3,433,437	3,046,742
Gross Unrealized Gains	344	28
Gross Unrealized Losses	(49,538)	(19,261)
Estimated Fair Value	3,384,243	3,027,509
Treasury bills
Marketable Securities [Line Items]
Amortized Cost	81,819	389,826
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(247)	(148)
Estimated Fair Value	$ 81,572	$ 389,678

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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