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Sum of investments and unrestricted cash as of the balance sheet date.

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Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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-SubTopic 210
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-Section S99
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Number of operating segments. An operating segment is a component of an enterprise: (a) that engages in business activities from which it may earn revenues and incur expenses (including revenues and expenses relating to transactions with other components of the same enterprise), (b) whose operating results are regularly reviewed by the enterprise's chief operating decision maker to make decisions about resources to be allocated to the segment and assess its performance, and (c) for which discrete financial information is available. An operating segment may engage in business activities for which it has yet to earn revenues, for example, start-up operations may be operating segments before earning revenues.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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-Name Accounting Standards Codification
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Number of segments reported by the entity. A reportable segment is a component of an entity for which there is an accounting requirement to report separate financial information on that component in the entity's financial statements.

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Equity impact of the value of new stock issued during the period. Includes shares issued in an initial public offering or a secondary public offering.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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Organization, Liquidity and Capital Resources - Additional Information (Details) $ in Millions		12 Months Ended
	Jan. 29, 2024 USD ($)	Dec. 31, 2023 USD ($) Segment	Dec. 31, 2021 USD ($)
Organization [Line Items]
Number of reportable segments \| Segment		1
Number of operating segments \| Segment		1
Issuance of common stock		$ 25	$ 220
Gilead \| Subsequent Event \| Third Stock Purchase Agreement Amendment
Organization [Line Items]
Issuance of common stock	$ 320
Cash, Cash Equivalents and Investments in Marketable Securities
Organization [Line Items]
Cash and investments		$ 866