Investments and Fair Value Measurements - Fair Value of Financial Assets (Details) - USD ($) $ in Thousands	Jul. 31, 2023	Jan. 31, 2023
Fair Value Measurements
U.S. treasury securities, corporate bonds and commercial paper	$ 1,036,390	$ 1,376,053
U.S. Government and Agency Securities
Assets:
Cash and cash equivalents	6,998	59,706
Commercial Paper
Assets:
Cash and cash equivalents	103,866
Estimate of Fair Value Measurement \| Recurring basis
Fair Value Measurements
Money market funds	781,543	316,943
Assets:
Cash and cash equivalents	892,407	376,649
Investments, current	925,526	1,316,347
Total	1,817,933	1,692,996
Estimate of Fair Value Measurement \| Recurring basis \| Level 1
Fair Value Measurements
Money market funds	781,543	316,943
Estimate of Fair Value Measurement \| Recurring basis \| Level 2
Fair Value Measurements
Money market funds	0	0
Estimate of Fair Value Measurement \| Recurring basis \| Level 3
Fair Value Measurements
Money market funds	0	0
U.S. Government and Agency Securities \| Investments, Current
Fair Value Measurements
U.S. treasury securities, corporate bonds and commercial paper	353,724	1,121,155
U.S. Government and Agency Securities \| Estimate of Fair Value Measurement \| Recurring basis
Fair Value Measurements
U.S. treasury securities, corporate bonds and commercial paper	360,722	1,180,861
U.S. Government and Agency Securities \| Estimate of Fair Value Measurement \| Recurring basis \| Level 1
Fair Value Measurements
U.S. treasury securities, corporate bonds and commercial paper	0	0
U.S. Government and Agency Securities \| Estimate of Fair Value Measurement \| Recurring basis \| Level 2
Fair Value Measurements
U.S. treasury securities, corporate bonds and commercial paper	360,722	1,180,861
U.S. Government and Agency Securities \| Estimate of Fair Value Measurement \| Recurring basis \| Level 3
Fair Value Measurements
U.S. treasury securities, corporate bonds and commercial paper	0	0
Corporate Bonds \| Investments, Current
Fair Value Measurements
U.S. treasury securities, corporate bonds and commercial paper	38,935	53,833
Corporate Bonds \| Estimate of Fair Value Measurement \| Recurring basis
Fair Value Measurements
U.S. treasury securities, corporate bonds and commercial paper	38,935	53,833
Corporate Bonds \| Estimate of Fair Value Measurement \| Recurring basis \| Level 1
Fair Value Measurements
U.S. treasury securities, corporate bonds and commercial paper	0	0
Corporate Bonds \| Estimate of Fair Value Measurement \| Recurring basis \| Level 2
Fair Value Measurements
U.S. treasury securities, corporate bonds and commercial paper	38,935	53,833
Corporate Bonds \| Estimate of Fair Value Measurement \| Recurring basis \| Level 3
Fair Value Measurements
U.S. treasury securities, corporate bonds and commercial paper	0	0
Commercial Paper \| Investments, Current
Fair Value Measurements
U.S. treasury securities, corporate bonds and commercial paper	532,867	141,359
Commercial Paper \| Estimate of Fair Value Measurement \| Recurring basis
Fair Value Measurements
U.S. treasury securities, corporate bonds and commercial paper	636,733	141,359
Commercial Paper \| Estimate of Fair Value Measurement \| Recurring basis \| Level 1
Fair Value Measurements
U.S. treasury securities, corporate bonds and commercial paper	0	0
Commercial Paper \| Estimate of Fair Value Measurement \| Recurring basis \| Level 2
Fair Value Measurements
U.S. treasury securities, corporate bonds and commercial paper	636,733	141,359
Commercial Paper \| Estimate of Fair Value Measurement \| Recurring basis \| Level 3
Fair Value Measurements
U.S. treasury securities, corporate bonds and commercial paper	$ 0	$ 0

Investments, Current, Fair Value Disclosure

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Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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Amount of 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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Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Investment in short-term money-market instruments (such as commercial paper, banker's acceptances, repurchase agreements, government securities, certificates of deposit, and so forth) which are highly liquid (that is, readily convertible to known amounts of cash) and so near their maturity that they present an insignificant risk of changes in value because of changes in interest rates. Generally, only investments with original maturities of three months or less qualify as cash equivalents by definition. Original maturity means an original maturity to the entity holding the investment. For example, both a three-month US Treasury bill and a three-year Treasury note purchased three months from maturity qualify as cash equivalents. However, a Treasury note purchased three-years ago does not become a cash equivalent when its remaining maturity is three months.

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