Stock compensation plans - Stock-based compensation expense and unrecognized compensation cost (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	$ 1,721	$ 1,216	$ 3,266	$ 1,470
Unrecognized compensation	20,295	10,917	$ 20,295	$ 10,917
Period for recognition			3 years	3 years 4 months 24 days
Stock Options \| Cost of goods sold
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	60	31	$ 107	$ 47
Stock Options \| Selling, general and administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	1,378	1,090	2,603	1,273
Stock Options \| Research and development
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	283	$ 95	556	$ 150
RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation	$ 3,033		$ 3,033
Period for recognition			3 years 9 months 18 days

Amount of expense for award under share-based payment arrangement. Excludes amount capitalized.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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Amount of cost not yet recognized for nonvested award under share-based payment arrangement.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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Weighted-average period over which cost not yet recognized is expected to be recognized for award under share-based payment arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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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.

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