| Summary of Significant Accounting Policies - Related parties (Details) - Immunocore - USD ($) $ in Thousands | 9 Months Ended | |
|---|---|---|
| Apr. 10, 2017 | Sep. 30, 2017 | |
| Related parties | ||
| Proceeds from sale of leasehold improvements on termination of lease agreement | $ 550,000 | |
| Maximum | ||
| Related parties | ||
| Percentage of shares ceased to be held by Immunocore | 5.00% | 
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- Definition Information pertains to percentage of share holding ceased to be held Immunocore. No definition available. 
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- Definition Information pertains to proceeds from sale of leasehold improvements on termination of lease agreement. No definition available. 
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. No definition available. 
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