Fair Value Measurements - Summary of Financial Assets Recognized at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023
Marketable securities:
Investment in Kyverna Therapeutics, Inc.	$ 4,390	$ 10,000
Fair Value on Recurring Basis [Member]
Assets
Cash equivalents and restricted cash equivalents	66,898	136,254
Marketable securities:
Marketable securities	672,548	785,339
Investment in Kyverna Therapeutics, Inc.	4,390
Total Assets	743,836	921,593
Fair Value on Recurring Basis [Member] \| U.S. Treasury and Other Government - Backed Securities [Member]
Marketable securities:
Marketable securities	352,616	382,308
Fair Value on Recurring Basis [Member] \| Financial Institution Debt Securities [Member]
Marketable securities:
Marketable securities	217,827	246,119
Fair Value on Recurring Basis [Member] \| Corporate Debt Securities [Member]
Marketable securities:
Marketable securities	94,927	97,408
Fair Value on Recurring Basis [Member] \| Other Asset Backed Securities [Member]
Marketable securities:
Marketable securities	7,178	59,504
Fair Value on Recurring Basis [Member] \| Level 1 [Member]
Assets
Cash equivalents and restricted cash equivalents	66,898	136,254
Marketable securities:
Marketable securities	169,735	120,556
Investment in Kyverna Therapeutics, Inc.	4,390
Total Assets	241,023	256,810
Fair Value on Recurring Basis [Member] \| Level 1 [Member] \| U.S. Treasury and Other Government - Backed Securities [Member]
Marketable securities:
Marketable securities	169,735	120,556
Fair Value on Recurring Basis [Member] \| Level 2 [Member]
Marketable securities:
Marketable securities	502,813	664,783
Total Assets	502,813	664,783
Fair Value on Recurring Basis [Member] \| Level 2 [Member] \| U.S. Treasury and Other Government - Backed Securities [Member]
Marketable securities:
Marketable securities	182,881	261,752
Fair Value on Recurring Basis [Member] \| Level 2 [Member] \| Financial Institution Debt Securities [Member]
Marketable securities:
Marketable securities	217,827	246,119
Fair Value on Recurring Basis [Member] \| Level 2 [Member] \| Corporate Debt Securities [Member]
Marketable securities:
Marketable securities	94,927	97,408
Fair Value on Recurring Basis [Member] \| Level 2 [Member] \| Other Asset Backed Securities [Member]
Marketable securities:
Marketable securities	$ 7,178	$ 59,504

Fair value portion of asset recognized for present right to economic benefit.

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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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Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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Fair value portion of investment securities, including, but not limited to, marketable securities, derivative financial instruments, and investments accounted for under the equity method.

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Fair value portion of investments in an entity not consolidated. Includes, but is not limited to, investments in an entity that is affiliated with the reporting entity by means of direct or indirect ownership, an entity in which the reporting entity shares control of the entity with another party or group, an entity which the company has significant influence, but does not have control and subsidiaries that are not required to be consolidated and are accounted for using the equity or cost method.

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