| Commitments and Contingencies - Leased property and equipment (Details) - USD ($) $ in Thousands | 12 Months Ended | ||
|---|---|---|---|
| Dec. 31, 2021 | Dec. 31, 2020 | Dec. 31, 2019 | |
| Capital Leased Assets [Line Items] | |||
| Gross | $ 433 | $ 2,213 | |
| Less: accumulated amortization | 186 | 801 | |
| Total | 247 | 1,412 | |
| Depreciation expense | 256 | 321 | $ 302 | 
| Leased Vehicles | |||
| Capital Leased Assets [Line Items] | |||
| Gross | $ 433 | 481 | |
| Leased Machinery and equipment | |||
| Capital Leased Assets [Line Items] | |||
| Gross | $ 1,732 | ||
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- Definition Amount before accumulated depreciation of leased physical assets used in the normal conduct of business to produce goods and services. Reference 1: http://fasb.org/us-gaap/role/ref/otherTransitionRef 
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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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- Definition The total gross amount less the charge for the use of the long-lived depreciable assets subject to a lease meeting the criteria for capitalization. Reference 1: http://fasb.org/us-gaap/role/ref/otherTransitionRef 
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- Definition The charge for the use of long-lived depreciable capital leased assets for the period. Reference 1: http://fasb.org/us-gaap/role/ref/otherTransitionRef 
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- Definition The total charge for the use of long-lived depreciable assets subject to a lease meeting the criteria for capitalization. Reference 1: http://fasb.org/us-gaap/role/ref/otherTransitionRef 
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