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Fair Value Measurements - Assets Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands | Sep. 30, 2025 | Dec. 31, 2024
--- | --- | ---
Financial Assets: |  |
Cash and cash equivalents: | $ 519,518 | $ 225,130
Amortized Cost or Carrying Value | 1,710,523 | 1,954,699
Amortized Cost or Carrying Value | 2,420 | 3,220
Amortized Cost or Carrying Value | 1,712,943 | 1,957,919
Total financial assets | 2,232,461 | 2,183,049
Gross Unrealized Gains | 11,204 | 7,685
Gross Unrealized Losses Less Than 12 Months | (75) | (1,890)
Gross Unrealized Losses More Than 12 Months | (5) | (612)
Marketable securities, aggregate fair value | 1,721,648 | 1,959,882
Equity securities, aggregate fair value | 2,420 | 3,220
Investments, aggregate fair value | 1,724,068 | 1,963,102
Total financial assets | 2,243,586 | 2,188,232
Level 1 |  |
Financial Assets: |  |
Cash and cash equivalents: | 453,807 | 210,071
Marketable securities, aggregate fair value | 251,327 | 400,564
Equity securities, aggregate fair value | 2,420 | 3,220
Investments, aggregate fair value | 253,747 | 403,784
Total financial assets | 707,554 | 613,855
Level 2 |  |
Financial Assets: |  |
Cash and cash equivalents: | 65,711 | 15,059
Marketable securities, aggregate fair value | 1,470,321 | 1,559,318
Equity securities, aggregate fair value | 0 | 0
Investments, aggregate fair value | 1,470,321 | 1,559,318
Total financial assets | 1,536,032 | 1,574,377
Level 3 |  |
Financial Assets: |  |
Cash and cash equivalents: | 0 | 0
Marketable securities, aggregate fair value | 0 | 0
Equity securities, aggregate fair value | 0 | 0
Investments, aggregate fair value | 0 | 0
Total financial assets | 0 | 0
U.S. Treasury securities |  |
Financial Assets: |  |
Amortized Cost or Carrying Value | 250,121 | 379,846
Gross Unrealized Gains | 1,206 | 1,243
Gross Unrealized Losses Less Than 12 Months | 0 | (296)
Gross Unrealized Losses More Than 12 Months | 0 | (55)
Marketable securities, aggregate fair value | 251,327 | 380,738
U.S. Treasury securities | Level 1 |  |
Financial Assets: |  |
Marketable securities, aggregate fair value | 251,327 | 380,738
U.S. Treasury securities | Level 2 |  |
Financial Assets: |  |
Marketable securities, aggregate fair value | 0 | 0
U.S. Treasury securities | Level 3 |  |
Financial Assets: |  |
Marketable securities, aggregate fair value | 0 | 0
Non-U.S. government securities |  |
Financial Assets: |  |
Amortized Cost or Carrying Value |  | 2,909
Gross Unrealized Gains |  | 27
Gross Unrealized Losses Less Than 12 Months |  | 0
Gross Unrealized Losses More Than 12 Months |  | 0
Marketable securities, aggregate fair value |  | 2,936
Non-U.S. government securities | Level 1 |  |
Financial Assets: |  |
Marketable securities, aggregate fair value |  | 2,936
Non-U.S. government securities | Level 2 |  |
Financial Assets: |  |
Marketable securities, aggregate fair value |  | 0
Non-U.S. government securities | Level 3 |  |
Financial Assets: |  |
Marketable securities, aggregate fair value |  | 0
Corporate debt securities and commercial paper |  |
Financial Assets: |  |
Amortized Cost or Carrying Value | 1,460,402 | 1,571,944
Gross Unrealized Gains | 9,998 | 6,415
Gross Unrealized Losses Less Than 12 Months | (75) | (1,594)
Gross Unrealized Losses More Than 12 Months | (5) | (557)
Marketable securities, aggregate fair value | 1,470,321 | 1,576,208
Corporate debt securities and commercial paper | Level 1 |  |
Financial Assets: |  |
Marketable securities, aggregate fair value | 0 | 16,890
Corporate debt securities and commercial paper | Level 2 |  |
Financial Assets: |  |
Marketable securities, aggregate fair value | 1,470,321 | 1,559,318
Corporate debt securities and commercial paper | Level 3 |  |
Financial Assets: |  |
Marketable securities, aggregate fair value | 0 | 0
Money market funds |  |
Financial Assets: |  |
Cash and cash equivalents: | 443,814 | 207,323
Money market funds | Level 1 |  |
Financial Assets: |  |
Cash and cash equivalents: | 443,814 | 207,323
Money market funds | Level 2 |  |
Financial Assets: |  |
Cash and cash equivalents: | 0 | 0
Money market funds | Level 3 |  |
Financial Assets: |  |
Cash and cash equivalents: | 0 | 0
Commercial paper |  |
Financial Assets: |  |
Cash and cash equivalents: | 65,711 | 15,059
Commercial paper | Level 1 |  |
Financial Assets: |  |
Cash and cash equivalents: | 0 |
Commercial paper | Level 2 |  |
Financial Assets: |  |
Cash and cash equivalents: | 65,711 | 15,059
Commercial paper | Level 3 |  |
Financial Assets: |  |
Cash and cash equivalents: | 0 |
U.S. Treasury securities |  |
Financial Assets: |  |
Cash and cash equivalents: | 9,993 | 2,748
U.S. Treasury securities | Level 1 |  |
Financial Assets: |  |
Cash and cash equivalents: | 9,993 | 2,748
U.S. Treasury securities | Level 2 |  |
Financial Assets: |  |
Cash and cash equivalents: | 0 | 0
U.S. Treasury securities | Level 3 |  |
Financial Assets: |  |
Cash and cash equivalents: | $ 0 | $ 0

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