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Significant Accounting Policies - Estimated Fair Value of Assets and Liability (Detail) - Fair Value, Measurements, Recurring - USD ($) $ in Thousands | Dec. 31, 2023 | Dec. 31, 2022
--- | --- | ---
Asset: |  |
Asset, fair value | $ 235,380 | $ 192,307
Level 1 |  |
Asset: |  |
Asset, fair value | 223,218 | 86,541
Level 2 |  |
Asset: |  |
Asset, fair value | 12,162 | 105,766
Money Market Fund |  |
Asset: |  |
Asset, fair value | 99,226 | 81,870
Money Market Fund | Level 1 |  |
Asset: |  |
Asset, fair value | 99,226 | 81,870
U.S. Treasury Shares |  |
Asset: |  |
Asset, fair value | 123,992 | 3,117
U.S. Treasury Shares | Level 1 |  |
Asset: |  |
Asset, fair value | 123,992 | 3,117
Agency Securities |  |
Asset: |  |
Asset, fair value | 8,912 | 1,554
Agency Securities | Level 1 |  |
Asset: |  |
Asset, fair value |  | 1,554
Agency Securities | Level 2 |  |
Asset: |  |
Asset, fair value | 8,912 |
Corporate Bonds |  |
Asset: |  |
Asset, fair value |  | 28,416
Corporate Bonds | Level 2 |  |
Asset: |  |
Asset, fair value |  | 28,416
Commercial Paper |  |
Asset: |  |
Asset, fair value |  | 62,347
Commercial Paper | Level 2 |  |
Asset: |  |
Asset, fair value |  | 62,347
Repo Securities |  |
Asset: |  |
Asset, fair value | 3,250 | 3,250
Repo Securities | Level 2 |  |
Asset: |  |
Asset, fair value | $ 3,250 | 3,250
Asset Backed Securities |  |
Asset: |  |
Asset, fair value |  | 1,260
Asset Backed Securities | Level 2 |  |
Asset: |  |
Asset, fair value |  | 1,260
Certificate of Deposit |  |
Asset: |  |
Asset, fair value |  | 9,100
Certificate of Deposit | Level 2 |  |
Asset: |  |
Asset, fair value |  | 9,100
Non-US Government |  |
Asset: |  |
Asset, fair value |  | 1,393
Non-US Government | Level 2 |  |
Asset: |  |
Asset, fair value |  | $ 1,393

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- Definition Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org//1943274/2147482106/820-10-50-2 + Details
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