Quarterly report pursuant to Section 13 or 15(d)

Organization and Description of Business Operations (Details Textual)

v3.10.0.1
Organization and Description of Business Operations (Details Textual) - USD ($)
$ / shares in Units, $ in Thousands
1 Months Ended 9 Months Ended
Mar. 31, 2018
Sep. 30, 2018
Sep. 30, 2017
Dec. 31, 2017
Retained Earnings (Accumulated Deficit)   $ (83,778)   $ (59,030)
Payments of Stock Issuance Costs   $ 2,184 $ 0  
National Securities Corporation [Member]        
Payments of Stock Issuance Costs $ 1,800      
Underwritten Public Offering [Member]        
Stock Issued During Period, Shares, New Issues 5,290,000      
Shares Issued, Price Per Share $ 4.35      
Stock Issued During Period, Value, New Issues $ 23,000      
Proceeds from Issuance Underwritten Public Offering 20,800      
Payments of Stock Issuance Costs $ 2,200      
Common Stock [Member]        
Shares Issued, Price Per Share   $ 4.33    
Stock Issued During Period Shares Common Shares For At The Market Offering   1,841,774    
Stock Issued During Period Value Common Shares For At The Market Offering Gross   $ 8,000    
Stock Issued During Period Value Common Shares For At The Market Offering   $ 7,700