Investments - Summary of Marketable Securities (Details) - USD ($) $ in Thousands	Jul. 31, 2026	Jan. 31, 2026
Marketable Securities [Line Items]
Amortized Cost	$ 6,359,544	$ 6,533,457
Gross Unrealized Gains	31	12,131
Gross Unrealized Losses	(41,846)	(1,557)
Estimated Fair Value	6,317,729	6,544,031
U.S. government agency securities
Marketable Securities [Line Items]
Amortized Cost	2,676,187	5,373,782
Gross Unrealized Gains	0	11,094
Gross Unrealized Losses	(24,707)	(989)
Estimated Fair Value	2,651,480	5,383,887
Agency bonds
Marketable Securities [Line Items]
Amortized Cost	928,486	1,095,004
Gross Unrealized Gains	13	1,032
Gross Unrealized Losses	(6,682)	(565)
Estimated Fair Value	921,817	1,095,471
Corporate and other debt securities
Marketable Securities [Line Items]
Amortized Cost	2,121,948
Gross Unrealized Gains	9
Gross Unrealized Losses	(10,448)
Estimated Fair Value	2,111,509
Treasury bills
Marketable Securities [Line Items]
Amortized Cost	114,957	64,671
Gross Unrealized Gains	8	5
Gross Unrealized Losses	(8)	(3)
Estimated Fair Value	114,957	$ 64,673
Commercial paper
Marketable Securities [Line Items]
Amortized Cost	517,966
Gross Unrealized Gains	1
Gross Unrealized Losses	(1)
Estimated Fair Value	$ 517,966