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Inventory - Narrative (Details) - USD ($) $ in Thousands | 12 Months Ended |
--- | --- | ---
Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018
Inventory Disclosure [Abstract] |  |  |
Inventory allowance, accrual | $ 251 | $ 3,758 |
Allowance for inventory obsolescence | $ 221 | $ 24 | $ 19

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