Cash Equivalents and Investments - Schedule of Debt Securities, Available-for-sale, Unrealized Loss Position, Fair Value (Details) - USD ($) $ in Thousands	Jul. 31, 2022	Jan. 31, 2022
Cash Equivalents, Fair Value
Less than 12 months, fair value	$ 77,679	$ 100,443
12 months or greater, fair value	0	0
Total, fair value	77,679	100,443
Cash Equivalents, Gross Unrealized Losses
Less than 12 months, accumulated losses	(21)	(5)
12 months or greater, accumulated losses	0	0
Total, accumulated losses	(21)	(5)
Investments, Fair Value
Less than 12 months, fair value	3,716,011	3,416,881
12 months or greater, fair value	76,587	8,935
Total, fair value	3,792,598	3,425,816
Investments, Gross Unrealized Losses
Less than 12 months, accumulated losses	(43,373)	(15,558)
12 months or greater, accumulated losses	(1,187)	(18)
Total, accumulated losses	(44,560)	(15,576)
Cash Equivalents And Debt Securities, Available-For-Sale [Abstract]
Less than 12 months, fair value	3,793,690	3,517,324
12 months or greater, fair value	76,587	8,935
Total, fair value	3,870,277	3,526,259
Cash Equivalents And Debt Securities, Available-For-Sale, Unrealized Loss Position, Accumulated Loss [Abstract]
Less than 12 months, accumulated losses	(43,394)	(15,563)
12 months or greater, accumulated losses	(1,187)	(18)
Total, accumulated losses	(44,581)	(15,581)
Commercial paper
Cash Equivalents, Fair Value
Less than 12 months, fair value	61,983	55,819
12 months or greater, fair value	0	0
Total, fair value	61,983	55,819
Cash Equivalents, Gross Unrealized Losses
Less than 12 months, accumulated losses	(14)	(2)
12 months or greater, accumulated losses	0	0
Total, accumulated losses	(14)	(2)
Investments, Fair Value
Less than 12 months, fair value	837,383	653,827
12 months or greater, fair value	0	0
Total, fair value	837,383	653,827
Investments, Gross Unrealized Losses
Less than 12 months, accumulated losses	(3,852)	(821)
12 months or greater, accumulated losses	0	0
Total, accumulated losses	(3,852)	(821)
U.S. government and agency securities
Cash Equivalents, Fair Value
Less than 12 months, fair value		36,995
12 months or greater, fair value		0
Total, fair value		36,995
Cash Equivalents, Gross Unrealized Losses
Less than 12 months, accumulated losses		(2)
12 months or greater, accumulated losses		0
Total, accumulated losses		(2)
Investments, Fair Value
Less than 12 months, fair value	369,879	334,980
12 months or greater, fair value	13,694	0
Total, fair value	383,573	334,980
Investments, Gross Unrealized Losses
Less than 12 months, accumulated losses	(9,334)	(2,558)
12 months or greater, accumulated losses	(306)	0
Total, accumulated losses	(9,640)	(2,558)
Corporate notes and bonds
Cash Equivalents, Fair Value
Less than 12 months, fair value	15,696	7,629
12 months or greater, fair value	0	0
Total, fair value	15,696	7,629
Cash Equivalents, Gross Unrealized Losses
Less than 12 months, accumulated losses	(7)	(1)
12 months or greater, accumulated losses	0	0
Total, accumulated losses	(7)	(1)
Investments, Fair Value
Less than 12 months, fair value	2,285,206	2,378,956
12 months or greater, fair value	62,893	8,935
Total, fair value	2,348,099	2,387,891
Investments, Gross Unrealized Losses
Less than 12 months, accumulated losses	(29,345)	(12,044)
12 months or greater, accumulated losses	(881)	(18)
Total, accumulated losses	(30,226)	(12,062)
Certificates of deposit
Investments, Fair Value
Less than 12 months, fair value	223,543	49,118
12 months or greater, fair value	0	0
Total, fair value	223,543	49,118
Investments, Gross Unrealized Losses
Less than 12 months, accumulated losses	(842)	(135)
12 months or greater, accumulated losses	0	0
Total, accumulated losses	$ (842)	$ (135)