Quarterly report pursuant to Section 13 or 15(d)

Fair Value Measurements - Additional Information (Details)

v3.8.0.1
Fair Value Measurements - Additional Information (Details) - USD ($)
$ in Thousands
3 Months Ended
Mar. 31, 2018
Mar. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Gain (loss) due to change in value of note payable $ (17) $ 232
Repayments of notes payable 0 4,667
Gain due to expiration of warrant liability $ 692 (7,294)
VenturEast | BioServe    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Number of shares associated with notes payable (in shares) 84,278  
Gain (loss) due to change in value of note payable $ 17 (232)
2016 Offerings | Significant Unobservable Inputs (Level 3) | Fair value measurements, recurring    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Gain due to expiration of warrant liability $ 692  
Loss on derivative warrants due to change in stock-price   $ (7,294)