Accrued Liabilities - Product Maintenance and Warranty (Details) - Warranty $ in Thousands  | 
6 Months Ended | 
|---|---|
| 
 Jun. 30, 2019  
USD ($) 
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| Accrued Liabilities, Rollforward [Roll Forward] | |
| Beginning Balance | $ 307 | 
| Additions for estimated future expense | 180 | 
| Incurred costs | (193) | 
| Closing Balance | $ 294 | 
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- Definition Accrued Liabilities, Rollforward [Roll Forward] No definition available. 
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- References No definition available. 
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- References No definition available. 
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- References No definition available. 
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- Details 
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