Organization and Description of Business Operations (Details Textual) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2018	Dec. 31, 2017
Retained Earnings (Accumulated Deficit)		$ (95,397)	$ (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 Net		$ 7,700