| Property, plant and equipment, net - Depreciation Expense (Details) - USD ($) | 12 Months Ended | ||
|---|---|---|---|
| Dec. 31, 2022 | Dec. 31, 2021 | Dec. 31, 2020 | |
| Property, plant and equipment, net | |||
| Depreciation expense | $ 5,266,000 | $ 5,630,000 | $ 6,627,000 | 
| X | ||||||||||
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- Definition The amount of expense recognized in the current period that reflects the allocation of the cost of tangible assets over the assets' useful lives. Includes production and non-production related depreciation. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef 
 | 
| X | ||||||||||
| 
- References No definition available. 
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