Note I - Preferred Stock and Warrants (Details Textual) - USD ($) $ / shares in Units, $ in Millions		1 Months Ended			12 Months Ended
	Jun. 02, 2014	May 31, 2015	Apr. 30, 2015	Feb. 28, 2015	Dec. 31, 2015	Dec. 31, 2013	Dec. 31, 2016
Preferred Stock, Shares Authorized		10,000,000	10,000,000		10,000,000		10,000,000
Preferred Stock, Par or Stated Value Per Share		$ 0.0001	$ 0.0001		$ 0.0001		$ 0.0001
Conversion of Preferred Stock to Common Stock Upon Initial Public Offering Shares					5,980,564
Preferred Stock, Shares Outstanding					0		0
2013 Warrants [Member]
Class of Warrant or Right Issued						1,079,453
Deerfield Warrant [Member]
Class of Warrant or Right Issued	14,423,076
Convertible Notes Payable [Member]
Debt Instrument, Face Amount						$ 3.8
Series D-1 Redeemable Convertible Preferred Stock [Member]
Conversion of Preferred Stock to Common Stock Upon Initial Public Offering Shares					415,584
Series D-1 Redeemable Convertible Preferred Stock [Member] | Cowen KP Investment LLC [Member]
Temporary Equity Shares Issuance				3,200,000
Sale of Stock, Price Per Share				$ 1.25
Proceeds from Issuance of Redeemable Convertible Preferred Stock				$ 4.0
Conversion of Preferred Stock to Common Stock Upon Initial Public Offering Shares				415,584
Series D Redeemable Convertible Preferred Stock [Member]
Conversion of Preferred Stock to Common Stock Upon Initial Public Offering Shares					967,786
Class of Warrant or Right, Number of Securities Called by Warrants or Rights			15,499,324			1,079,453
IPO [Member]
Stock Issued During Period, Shares, Conversion of Convertible Securities		5,980,564
Common Stock [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights			2,066,543			143,466
Class of Warrant or Right, Exercise Price of Warrants or Rights						$ 5.85
Common Stock [Member] | Deerfield Warrant [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
Common Stock [Member] | IPO [Member]
Stock Issued During Period, Shares, Conversion of Convertible Securities			5,980,564		5,980,564