| Contingencies and commitments - MD Anderson Strategic Alliance (Details) - MD Anderson Strategic Alliance - USD ($) | 12 Months Ended | |||||
|---|---|---|---|---|---|---|
| Dec. 31, 2022 | Dec. 31, 2021 | Dec. 31, 2020 | Dec. 31, 2018 | Dec. 31, 2017 | Sep. 26, 2016 | |
| Contingencies and commitments | ||||||
| Upfront payment | $ 3,412,000 | |||||
| Milestone Payments | $ 454,000 | $ 3,549,000 | $ 2,326,000 | |||
| Milestone met and paid in current period | $ 2,326,000 | |||||
| Minimum | ||||||
| Contingencies and commitments | ||||||
| Potential milestone payments | $ 19,644,000 | |||||
| X | ||||||||||
| 
- Definition Represents the amount of payments that the entity is required to make under the agreement, upon achievement of certain development and product milestones. No definition available. 
 | 
| X | ||||||||||
| 
- Definition Represents the amount of payments that the entity is required to make under the agreement, upon achievement of certain development and product milestones No definition available. 
 | 
| X | ||||||||||
| 
- Definition Represents the amount of payments that the entity is required to make under the agreement, upon achievement of certain development and product milestones. No definition available. 
 | 
| X | ||||||||||
| 
- Definition Amount of up-front payment under terms of the agreement. No definition available. 
 | 
| X | ||||||||||
| 
- 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. 
 | 
| X | ||||||||||
| 
- Details 
 | 
| X | ||||||||||
| 
- Details 
 |