Note 8 - Common Stock (Details Textual) - USD ($)						1 Months Ended				3 Months Ended		9 Months Ended
	May 31, 2017	May 22, 2017	Mar. 22, 2017	Jun. 20, 2016	Jun. 17, 2016	May 31, 2017	May 19, 2017	Aug. 30, 2016	Jul. 31, 2016	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	May 31, 2015	Sep. 30, 2014
Proceeds from Issuance of Common Stock												$ 31,440,000	$ 13,886,000
Class of Warrant or Right, Number of Securities Called by Warrants or Rights										642,622		642,622
Debt Instrument, Unamortized Discount										$ 1,620,000		$ 1,620,000
Class of Warrants or Rights, Exercises in Period												4,701	25,268
Allocated Share-based Compensation Expense										487,000	$ 272,000	$ 1,314,000	$ 662,000
The 2016 Loan Agreement [Member]
Amortization of Debt Discount (Premium)										0	35,000	371,000	35,000
Debt Issuance Costs, Net				$ 90,000
Debt Instrument, Unamortized Discount										0		0
The 2017 Loan Agreement [Member]
Amortization of Debt Discount (Premium)										68,000		106,000
Debt Issuance Costs, Net	$ 786,000					$ 786,000
Debt Instrument, Unamortized Discount										$ 1,620,000		$ 1,620,000
September 2014 Issuance Related to 2014 Loan Agreement [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
Amortization of Debt Discount (Premium)											0		387,000
Stock Issued During Period, Shares, Exercise of Warrants								17,295
May 2015 Issuance Related to 2014 Loan Agreement [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights														3,125
Class of Warrant or Right, Exercise Price of Warrants or Rights														$ 2.96
Stock Issued During Period, Shares, Exercise of Warrants									885
June 2016 Issuance Related to 2016 Loan Agreement [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights				100,402						100,402		100,402
Class of Warrant or Right, Exercise Price of Warrants or Rights				$ 4.98						$ 4.98		$ 4.98
Warrants and Rights Outstanding				$ 350,000
Warrant Term				10 years
May 2017 Issuance Related to 2017 Loan Agreement [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights	222,049	222,049				222,049				222,049		222,049
Class of Warrant or Right, Exercise Price of Warrants or Rights	$ 9.50	$ 9.50				$ 9.50				$ 9.50		$ 9.50
Warrants and Rights Outstanding	$ 940,000					$ 940,000
Warrant Term		10 years				10 years
Fair Value Assumptions, Expected Dividend Rate						0.00%
Fair Value Assumptions, Expected Volatility Rate						55.10%
Fair Value Assumptions, Risk Free Interest Rate						2.25%
Fair Value Assumptions, Expected Term	10 years
Allocated Share-based Compensation Expense										$ 0	$ 0	$ 162,000	$ 9
Vendors and Contractors Warrants, October and November 2014 Issuance [Member]
Class of Warrant or Right Number of Securities Called by Warrants or Rights Cancelled In Period												0	1,094
March 2017 Offering [Member]
Stock Issued During Period, Shares, New Issues			8,625,000
Share Price			$ 4
Proceeds from Issuance of Common Stock			$ 34,500,000
Proceeds From Issuance of Common Stock, Net			$ 31,440,000
June 2016 Offering [Member]
Stock Issued During Period, Shares, New Issues					3,105,000
Share Price					$ 5
Proceeds from Issuance of Common Stock					$ 15,525,000
Proceeds From Issuance of Common Stock, Net					$ 13,886,000
Restricted Stock [Member]
Stock Issued During Period, Shares, New Issues							35,000
Shares Issued, Price Per Share							$ 7.42
Stock Issued During Period, Value, New Issues							$ 260,000