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Stockholders' equity - Award plans and inducement grants (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Stock-based compensation
Stock options	4,700	4,700	4,560
RSUs	175,086	141,361
Remaining shares of common stock available for future issuance	361,158
2022 Plan
Stock-based compensation
Remaining shares of common stock available for future issuance	356,992
2021 Inducement Plan
Stock-based compensation
Remaining shares of common stock available for future issuance	4,166
Stock Plan 2019, 2022 And Inducement Plan
Stock-based compensation
Unrecognized share-based compensation cost	$ 0.6
Unrecognized share-based compensation - Weighted average period	1 year 8 months 12 days
Employee Stock Option
Stock-based compensation
Stock options	4,700
Employee Stock Option \| 2019 Plan
Stock-based compensation
Stock options	1,575
Employee Stock Option \| 2022 Plan
Stock-based compensation
Stock options	3,125
Restricted stock units
Stock-based compensation
RSUs	175,086
Restricted stock units \| 2022 Plan
Stock-based compensation
RSUs	175,086