Statements of Shareholders' Equity - USD ($)	Total	January 2019 Financing Transaction [Member]	February 2019 Financing Transaction [Member]	January 2019 Financing Transaction Overallotment [Member]	March 2019 Financing Transaction [Member]	Common Stock [Member]	Common Stock [Member] January 2019 Financing Transaction [Member]	Common Stock [Member] February 2019 Financing Transaction [Member]	Common Stock [Member] January 2019 Financing Transaction Overallotment [Member]	Common Stock [Member] March 2019 Financing Transaction [Member]	SeriesA Convertible Preferred Stock [Member]	Additional Paid-in Capital [Member]	Additional Paid-in Capital [Member] January 2019 Financing Transaction [Member]	Additional Paid-in Capital [Member] February 2019 Financing Transaction [Member]	Additional Paid-in Capital [Member] January 2019 Financing Transaction Overallotment [Member]	Additional Paid-in Capital [Member] March 2019 Financing Transaction [Member]	Accumulated Deficit [Member]
Beginning balance at Dec. 31, 2017	$ 1,296,034					$ 118						$ 196,545,523					$ (195,249,607)
Beginning balance, shares at Dec. 31, 2017						1,181,179
Stock-based compensation expense	225,263											225,263
Shares and warrants issued, net of issuance costs		$ 13,342,821					$ 110						$ 13,342,711
Shares and warrants issued, net of issuance costs, shares							1,095,153
Adjustment for presentation after reverse stock split						$ 6,576						(6,576)
Net loss	(6,356,404)																(6,356,404)
Ending balance at Mar. 31, 2018	8,507,714					$ 6,804						210,106,921					(201,606,011)
Ending balance, shares at Mar. 31, 2018						2,276,332
Beginning balance at Dec. 31, 2017	1,296,034					$ 118						196,545,523					(195,249,607)
Beginning balance, shares at Dec. 31, 2017						1,181,179
Net loss	(24,600,000)
Ending balance at Dec. 31, 2018	3,042,519					$ 463						223,499,634					(220,457,578)
Ending balance, shares at Dec. 31, 2018						4,629,174					4,417
Stock-based compensation expense	102,459											102,459
Shares issued upon exercise of common stock warrants	4,748					$ 1						4,747
Shares issued upon exercise of common stock warrants, shares						5,985
Deemed dividends related warrants down round provision	99,743											99,743					(99,743)
Shares and warrants issued, net of issuance costs		$ 2,032,311	$ 6,602,735	$ 592,306	$ 7,553,793		$ 99	$ 625	$ 54	$ 595			$ 2,032,212	$ 6,602,110	$ 592,252	$ 7,553,198
Shares and warrants issued, net of issuance costs, shares							990,000	6,250,000	538,867	5,950,000
Shares issued upon conversion of preferred stock						$ 50						(50)
Shares issued upon conversion of preferred stock, shares						503,438					(2,278)
Net loss	(5,916,787)																(5,916,787)
Ending balance at Mar. 31, 2019	$ 14,014,084					$ 1,887						$ 240,486,305					$ (226,474,108)
Ending balance, shares at Mar. 31, 2019						18,867,464					2,139