Common Stock Warrants and Common Stock Warrant Liability (Details) - $ / shares		3 Months Ended	12 Months Ended
		Mar. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Outstanding at beginning		11,226,821	6,431,785	829,285
Warrants issued
Warrants exercised		(31,811)
Expired Warrants			(488,119)
Date Issued		2018-08
Exercise Price (in dollars per share)		$ 1.15
Outstanding at ending		11,195,010	11,226,821	6,431,785
Warrants issued [Member]
Warrants issued			1,133,909
Date Issued			2018-06
Term			5 years
Exercise Price (in dollars per share)			$ 1.82
Common Stock Offering Warrants Issued [Member]
Warrants issued			5,357,052	4,657,500
Date Issued			2018-08	2017-11
Term			5 years	5 years
Exercise Price (in dollars per share)	[1]		$ 1.15	$ 1.50
Common Stock Offering - Dealer Manager Warrants [Member]
Warrants issued			267,853
Date Issued			2018-08
Term			5 years
Exercise Price (in dollars per share)			$ 1.725
Common Stock Offering Underwriter Warrants [Member]
Warrants issued				945,000
Date Issued				2017-11
Term				5 years
Exercise Price (in dollars per share)				$ 1.50

[1] The common stock warrants issued in November 2017 with an initial exercise price of $1.50 per share adjusted downward to $0.95 per share effective July 24, 2018 in connection with our Rights Offering, and may be subject to further downward adjustments, pursuant to antidilution price adjustment protection contained within those warrants.