Long-Term Debt and Other Financings - Interest Expense and Amortization of Debt Issuance Costs (Details) - USD ($) $ in Thousands  | 
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2017  | 
Dec. 31, 2016  | 
Dec. 31, 2015  | 
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| Interest expense and amortization of debt issuance costs [Abstract] | |||
| Interest expense | $ 1,238 | $ 3,946 | $ 3,765 | 
| Hercules Loan [Member] | |||
| Interest expense and amortization of debt issuance costs [Abstract] | |||
| Interest expense | 311 | 2,628 | 2,223 | 
| Servier Loan [Member] | |||
| Interest expense and amortization of debt issuance costs [Abstract] | |||
| Interest expense | 431 | 892 | 1,083 | 
| Novartis Note [Member] | |||
| Interest expense and amortization of debt issuance costs [Abstract] | |||
| Interest expense | 490 | 405 | 329 | 
| Other [Member] | |||
| Interest expense and amortization of debt issuance costs [Abstract] | |||
| Interest expense | $ 6 | $ 21 | $ 130 | 
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- References No definition available. 
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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/presentationRef 
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