Quarterly report pursuant to Section 13 or 15(d)

Fair Value Measurements - Outstanding Long Term Debt Carrying Amount and Estimated Fair Value (Details)

v3.19.1
Fair Value Measurements - Outstanding Long Term Debt Carrying Amount and Estimated Fair Value (Details) - USD ($)
$ in Thousands
Mar. 31, 2019
Dec. 31, 2018
Carrying Amount [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Long-term debt $ 22,583 $ 22,479
Carrying Amount [Member] | Novartis Note [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Long-term debt 15,193 15,193
Carrying Amount [Member] | SVB Loan [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Long-term debt 7,390 7,286
Fair Value [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Long-term debt 22,518 22,106
Fair Value [Member] | Novartis Note [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Long-term debt 15,130 14,825
Fair Value [Member] | SVB Loan [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Long-term debt $ 7,388 $ 7,281