| Summary of Significant Accounting Policies - Components of Inventory (Details) - USD ($) $ in Thousands | Dec. 31, 2017 | Dec. 31, 2016 | 
|---|---|---|
| Accounting Policies [Abstract] | ||
| Raw materials | $ 1,269 | $ 1,404 | 
| Work in process | 245 | 466 | 
| Finished goods | 17 | 866 | 
| Total inventory | $ 1,531 | $ 2,736 | 
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- References No definition available. 
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- Definition Amount before valuation and LIFO reserves of completed merchandise or goods expected to be sold within one year or operating cycle, if longer. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- Definition Amount after valuation and LIFO reserves of inventory expected to be sold, or consumed within one year or operating cycle, if longer. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- Definition Amount before valuation and LIFO reserves of raw materials expected to be sold, or consumed within one year or operating cycle, if longer. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- Definition Amount before valuation and LIFO reserves of merchandise or goods in the production process expected to be completed within one year or operating cycle, if longer. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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