Note F - Common Stock and Warrants (Details Textual) - USD ($)					6 Months Ended	12 Months Ended	23 Months Ended
	Oct. 25, 2018	Oct. 10, 2018	Oct. 05, 2018	Jun. 02, 2014	Jun. 30, 2019	Dec. 31, 2013	Sep. 04, 2018	Dec. 31, 2018
Common Stock, Shares Authorized					250,000,000			250,000,000
Common Stock, Shares, Issued, Total					28,858,543			26,455,352
Common Stock [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights						143,466
Class of Warrant or Right, Exercise Price of Warrants or Rights						$ 5.85
2013 Warrants [Member]
Debt Instrument, Face Amount						$ 3,800,000
Class of Warrant or Right Issued						1,079,453
Series D Redeemable Convertible Preferred Stock [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights						1,079,453
Deerfield Warrant [Member]
Class of Warrant or Right Issued				14,423,076
Deerfield Warrant [Member] | Common Stock [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights				1,923,077
Class of Warrant or Right, Exercise Price of Warrants or Rights				$ 5.85
Warrant Issued to KVK [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights	500,000
Class of Warrant or Right, Exercise Price of Warrants or Rights	$ 2.30
Class of Warrant or Right, Additional Shares Exercisable for Each Milestones	125,000
Series A Preferred Stock Converted Into Common Stock [Member]
Conversion of Stock, Shares Converted					6,240
Conversion of Stock, Shares Issued					2,080,000
Exchanged 2021 Notes for Series A Preferred Stock [Member]
Debt Conversion, Converted Instrument, Shares Issued			9,577
Second ATM Agreement [Member]
Stock Issued During Period, Shares, New Issues					0
Cowen and Company, LLC [Member]
Stock Issued During Period, Shares, New Issues							762,338
Proceeds from Issuance of Common Stock							$ 4,900,000
RBC Capital Markets, LLC [Member] | Underwriting Agreement [Member]
Stock Issued During Period, Shares, New Issues		8,333,334	8,333,334