Note 11 - Stockholders' Equity (Details Textual) - USD ($)						1 Months Ended			3 Months Ended	38 Months Ended
	Oct. 02, 2015	May. 27, 2015	Jun. 20, 2014	Jan. 15, 2014	Feb. 02, 2013	Sep. 30, 2015	Jun. 20, 2014	Feb. 25, 2013	Mar. 31, 2016	Mar. 31, 2016	Dec. 31, 2015
May 2015 Common Stock Offering [Member]
Stock Issued During Period, Shares, New Issues		3,000,000
Share Price		$ 2.675
Proceeds from Issuance of Common Stock Gross		$ 8,000,000
Class of Warrant or Right, Exercise Price of Warrants or Rights		$ 2.60
Class of Warrant or Right, Number of Securities Called by Each Warrant or Right		0.65
Class of Warrant or Right, Number of Securities Called by Warrants or Rights		1,950,000
Warrants Issued Expiration Period		5 years
Common Stock Offering PeriodOfRestriction		150 days
January Two Thousand Fourteen Common Stock Offering [Member] | Series A Warrant [Member]
Class of Warrant or Right, Number of Securities Called by Each Warrant or Right				0.25
Warrants Issued Expiration Period				5 years
January Two Thousand Fourteen Common Stock Offering [Member] | Series B Warrant [Member]
Class of Warrant or Right, Number of Securities Called by Each Warrant or Right				0.25
January Two Thousand Fourteen Common Stock Offering [Member]
Stock Issued During Period, Shares, New Issues				3,603,604
Share Price				$ 4.1625
Class of Warrant or Right, Exercise Price of Warrants or Rights				$ 4.10
Class of Warrant or Right, Number of Securities Called by Warrants or Rights				1,801,802
Common Stock, Par or Stated Value Per Share				$ 0.01
Stock Issued During Period, Value, New Issues				$ 15,000,000
Common Stock Shares per Unit				1
ATM Agreement [Member]
Stock Issued During Period, Shares, New Issues										1,479,535
Aggregate Offering Price					$ 25,000,000				$ 17,400,000
Proceeds from Issuance of Common Stock										$ 7,400,000
Commission on Proceeds from ATM Shares Percent								3.00%
Legal Fees								$ 50,000
Aggregate Offering Price, Additions	$ 7,500,000
EGEN Inc [Member]
Share Price			$ 3.48				$ 3.48
Stock Issued During Period, Shares, Acquisitions			2,712,188				2,712,188		2,712,188
Business Acquisition, Equity Interest Issued or Issuable, Number of Shares							670,070		670,070
Shelf Registration Statement Amount						$ 75,000,000
Class of Warrant or Right, Exercise Price of Warrants or Rights									$ 6.37	$ 6.37	$ 6.37
Common Stock, Par or Stated Value Per Share									$ 0.01	$ 0.01	$ 0.01
Aggregate Offering Price, Additions									$ 7,500,000