Note 7 - Common Stock (Details Textual) - USD ($)	1 Months Ended				3 Months Ended		12 Months Ended
	Mar. 31, 2016	Dec. 31, 2015	May. 31, 2015	Sep. 30, 2014	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015	May. 30, 2015	Feb. 28, 2015	Nov. 30, 2014
May 2015 Issuance [Member]
Allocated Share-based Compensation Expense					$ 0	$ 0
Class of Warrant or Right, Number of Securities Called by Warrants or Rights			36,229
Class of Warrant or Right, Exercise Price of Warrants or Rights			$ 4.24
Fair Value Assumptions, Expected Term			10 years
March 2015 Issuance [Member]
Allocated Share-based Compensation Expense					0	$ 3,000
Class of Warrant or Right, Number of Securities Called by Warrants or Rights						1,454
Class of Warrant or Right, Exercise Price of Warrants or Rights						$ 2.72
May 2015 Issuance Second Contractor [Member]
Allocated Share-based Compensation Expense					0	$ 0
Class of Warrant or Right, Number of Securities Called by Warrants or Rights								21,585
Class of Warrant or Right, Exercise Price of Warrants or Rights								$ 4.24
Fair Value Assumptions, Expected Term			5 years
December 2015 Issuance [Member]
Allocated Share-based Compensation Expense					0	0
Class of Warrant or Right, Number of Securities Called by Warrants or Rights		26,875					26,875
Class of Warrant or Right, Exercise Price of Warrants or Rights		$ 5.60					$ 5.60
Warrant Term		10 years
March 2016 Issuance [Member]
Allocated Share-based Compensation Expense					$ 142,000
Class of Warrant or Right, Number of Securities Called by Warrants or Rights	25,000				25,000
Class of Warrant or Right, Exercise Price of Warrants or Rights	$ 6.08				$ 6.08
Warrant Term					10 years
Fair Value Assumptions, Expected Dividend Rate					0.00%
Fair Value Assumptions, Expected Volatility Rate					72.10%
Fair Value Assumptions, Risk Free Interest Rate					1.78%
Private Placement [Member]
Class of Warrant or Right, Outstanding	401,446				401,446
Class of Warrant or Right, Number of Securities Called by Warrants or Rights	117,535				117,535
Class of Warrant or Right, Exercise Price of Warrants or Rights	$ 4.24				$ 4.24
Warrant Term					5 years
Class of Warrants or Rights, Exercises in Period	6,250						735
September 2014 Term Loan [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights				58,962
Class of Warrant or Right, Exercise Price of Warrants or Rights				$ 4.24
Warrant Term				10 years
Amortization of Debt Discount (Premium)					$ 45,000	48,000
Unamortized Debt Issuance Expense	$ 342,000				342,000
Warrant [Member] | Vendors And Nonemployee [Member]
Allocated Share-based Compensation Expense					0	15,000
Warrant [Member] | Employees [Member]
Allocated Share-based Compensation Expense					0	244,000
Warrant [Member] | September 2014 Term Loan [Member]
Fair Value Assumptions, Expected Term			10 years
Vendors And Nonemployee [Member]
Class of Warrant or Right Number of Securities Called by Warrants or Rights Cancelled In Period	625						5,157
September 2014 Term Loan [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights			3,125	58,962
Class of Warrant or Right, Exercise Price of Warrants or Rights			$ 2.96	$ 4.24
Warrant Term			10 years	10 years
Amortization of Debt Discount (Premium)					0	0
Unamortized Debt Issuance Expense	$ 0				0	0
Allocated Share-based Compensation Expense					$ 188,000	$ 42,000
Class of Warrant or Right, Number of Securities Called by Warrants or Rights	401,446				401,446				75,697	47,751
Class of Warrant or Right, Exercise Price of Warrants or Rights									$ 4	$ 4.24
Percent Of Outstanding Loan Amount	1.00%				1.00%