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Investments - Investments Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands | 9 Months Ended | 12 Months Ended
--- | --- | ---
Sep. 30, 2025 | Dec. 31, 2024
Schedule Of Available For Sale Securities [Line Items] |  |
Short-term investments, Estimated Fair Value | $ 454,378 | $ 502,933
Fair Value Measurements on Recurring Basis |  |
Schedule Of Available For Sale Securities [Line Items] |  |
Cash equivalents, Amortized Cost | 46,640 |
Cash equivalents, Estimated Fair Value | 46,640 |
Short-term investments, Amortized Cost | 453,460 | 502,169
Short-term investments, Unrealized Gains | 924 | 766
Short-term investments, Unrealized Losses | (6) | (2)
Short-term investments, Estimated Fair Value | 454,378 | 502,933
Cash equivalents and Short-term investments, Amortized Cost | 500,100 | 702,193
Cash equivalents and Short-term investments, Unrealized Gains | 924 | 766
Cash equivalents and Short-term investments, Unrealized Losses | (6) | (2)
Cash equivalents and Short-term investments, Estimated Fair Value | 501,018 | 702,957
Fair Value Measurements on Recurring Basis | Money Market Funds |  |
Schedule Of Available For Sale Securities [Line Items] |  |
Cash equivalents, Amortized Cost | 39,180 | 200,024
Cash equivalents, Estimated Fair Value | $ 39,180 | $ 200,024
Fair Value Measurements on Recurring Basis | Money Market Funds | Maximum |  |
Schedule Of Available For Sale Securities [Line Items] |  |
Maturities (years) | 1 year | 1 year
Fair Value Measurements on Recurring Basis | U.S. Treasury Securities |  |
Schedule Of Available For Sale Securities [Line Items] |  |
Cash equivalents, Amortized Cost | $ 7,460 |
Cash equivalents, Estimated Fair Value | 7,460 |
Short-term investments, Amortized Cost | 420,960 | $ 497,172
Short-term investments, Unrealized Gains | 915 | 766
Short-term investments, Unrealized Losses | (1) |
Short-term investments, Estimated Fair Value | $ 421,874 | $ 497,938
Fair Value Measurements on Recurring Basis | U.S. Treasury Securities | Maximum |  |
Schedule Of Available For Sale Securities [Line Items] |  |
Maturities (years) | 1 year |
Maturities (years) | 2 years | 3 years
Fair Value Measurements on Recurring Basis | U.S. Agency Bonds |  |
Schedule Of Available For Sale Securities [Line Items] |  |
Short-term investments, Amortized Cost | $ 32,500 | $ 4,997
Short-term investments, Unrealized Gains | 9 |
Short-term investments, Unrealized Losses | (5) | (2)
Short-term investments, Estimated Fair Value | $ 32,504 | $ 4,995
Fair Value Measurements on Recurring Basis | U.S. Agency Bonds | Maximum |  |
Schedule Of Available For Sale Securities [Line Items] |  |
Maturities (years) | 3 years | 3 years

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