Income Taxes - Schedule of Operating Loss Carryforwards and Research Tax Credits (Details) - USD ($) $ in Thousands |
Dec. 31, 2025 |
Dec. 31, 2024 |
|---|---|---|
| UK | ||
| Operating Loss Carryforwards [Line Items] | ||
| Operating loss carryforwards and research tax credits | $ 557,930 | $ 365,638 |
| U.S. | ||
| Operating Loss Carryforwards [Line Items] | ||
| Operating loss carryforwards and research tax credits | $ 35,197 | $ 33,423 |