Stock Purchase Warrants (Details Textual) - USD ($)	1 Months Ended			3 Months Ended
	Dec. 26, 2017	Nov. 18, 2016	Oct. 10, 2014	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Equity, Class of Treasury Stock [Line Items]
Warrants Not Settleable in Cash, Fair Value Disclosure	$ 9,000
Change in fair value of warrant liability				$ (2,655,000)	$ (5,090,000)
Warrant liabilities				1,428,000		$ 4,083,000
Consulting Agreement Term	6 months
Warrant [Member]
Equity, Class of Treasury Stock [Line Items]
Share Based Compensation Arrangement By Share Based Payment Award Non Option Equity Instruments Warrants Exercisable Number	25,000
Stock Warrants [Member]
Equity, Class of Treasury Stock [Line Items]
Sale of Stock, Price Per Share			$ 1.47
Change in fair value of warrant liability			$ 7,400,000	326,000,000	1,000,000
Proceeds from Issuance of Common Stock			$ 19,100,000
Sale of Stock, Number of Shares Issued in Transaction			14,059,616
Issuance Of Warrants To Purchase Of Common Stock			0.5
Share-Based Compensation Arrangement By Share-Based Payment Award, Options, Exercisable, Number			7,029,808
Share Based Compensation Arrangement By Share Based Payment Award Warrants Vested and Expected To Vest Outstanding Number			1.75
Warrant liabilities				90,000	1,100,000
IPO [Member]
Equity, Class of Treasury Stock [Line Items]
Sale of Stock, Price Per Share		$ 1.00
Stock Issued During Period, Shares, New Issues		25,000,000
Class of Warrant or Right, Number of Securities Called by Warrants or Rights		50,000,000
Warrants Not Settleable in Cash, Fair Value Disclosure		$ 15,700,000		1,300,000	8,600,000
Change in fair value of warrant liability				$ 2,300,000	$ 4,100,000
IPO [Member] | Series A [Member]
Equity, Class of Treasury Stock [Line Items]
Class of Warrant or Right, Exercise Price of Warrants or Rights		$ 1.43
IPO [Member] | Series B [Member]
Equity, Class of Treasury Stock [Line Items]
Class of Warrant or Right, Exercise Price of Warrants or Rights		$ 1.72