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Fair Value Measurements - Additional Information (Details) - USD ($) $ in Thousands | 3 Months Ended | 9 Months Ended |
--- | --- | --- | ---
Sep. 30, 2023 | Sep. 30, 2022 | Sep. 30, 2023 | Sep. 30, 2022 | Dec. 31, 2022
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |  |  |  |
Estimated fair value of equity securities | $ 34,043 |  | $ 34,043 |  | $ 32,020
Unrealized gain on equity securities | 694 | $ 3,496 | 2,023 | $ 323 |
Vaxcyte, Inc. | Vaxcyte Common Stock |  |  |  |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |  |  |  |
Estimated fair value of equity securities | 34,000 |  | 34,000 |  | $ 32,000
Unrealized gain on equity securities | $ 700 | $ 3,500 | $ 2,000 | $ 300 |
Vaxcyte, Inc. | Equity Securities | Vaxcyte Common Stock |  |  |  |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |  |  |  |
Number of shares held | 667,780 |  | 667,780 |  | 667,780
Fair Value Measurements Recurring |  |  |  |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |  |  |  |
Securities held | $ 353,029 |  | $ 353,029 |  | $ 330,430

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