Quarterly report pursuant to Section 13 or 15(d)

Capital Stock - Rights Offerring 2018 - Additional Information (Details)

v3.19.1
Capital Stock - Rights Offerring 2018 - Additional Information (Details) - USD ($)
$ / shares in Units, $ in Millions
 1 Months Ended 3 Months Ended
Dec. 31, 2018
Feb. 28, 2017
Mar. 31, 2019
Mar. 31, 2018
Nov. 19, 2018
Class Of Warrant Or Right [Line Items]          
Aggregate gross proceeds from issuance of common stock and preferred stock $ 20.0        
Offering costs offset against proceeds sale of common stock and preferred stock 0.3        
Net proceeds from issuance of common stock and preferred stock $ 19.7        
Preferred stock, stated value $ 0.05   $ 0.05    
BVF [Member]          
Class Of Warrant Or Right [Line Items]          
Ownership percentage on outstanding shares     19.99%    
Ownership percentage on outstanding shares     53.40%    
Series Y Preferred Stock [Member]          
Class Of Warrant Or Right [Line Items]          
Total number of shares issued 1,252.772        
Series Y Convertible Preferred Stock [Member]          
Class Of Warrant Or Right [Line Items]          
Preferred stock, stated value $ 13,000        
Conversion of preferred stock into registered common stock 1,000        
Preferred stock conversion price per share $ 13.00        
Total number of shares of common stock issued upon conversion 1,252,772        
Percentage of convertible preferred stock conversion blocker provision 19.99%        
Series X and Series Y Convertible Preferred Stock [Member]          
Class Of Warrant Or Right [Line Items]          
Conversion of preferred stock into registered common stock 1,000        
Preferred shares converted     0    
Common Stock [Member]          
Class Of Warrant Or Right [Line Items]          
Total number of shares issued 285,689 1,200,000   68,000  
Common Stock [Member] | Series X Preferred Stock [Member]          
Class Of Warrant Or Right [Line Items]          
Rights offering amount         $ 20.0