| Long-Term Debt and Other Financings - Interest Expense (Details) - USD ($) $ in Thousands | 3 Months Ended | 6 Months Ended | ||
|---|---|---|---|---|
| Jun. 30, 2020 | Jun. 30, 2019 | Jun. 30, 2020 | Jun. 30, 2019 | |
| Interest expense | ||||
| Interest expense | $ 508 | $ 423 | $ 1,050 | $ 852 | 
| Silicon Valley Bank Loans | ||||
| Interest expense | ||||
| Interest expense | 356 | 236 | 739 | 477 | 
| Novartis Note | ||||
| Interest expense | ||||
| Interest expense | 151 | 186 | 309 | 372 | 
| Other | ||||
| Interest expense | ||||
| Interest expense | $ 1 | $ 1 | $ 2 | $ 3 | 
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- Definition Amount of the cost of borrowed funds accounted for as interest expense for debt. Reference 1: http://www.xbrl.org/2003/role/disclosureRef 
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