Note 11 - Warrant Liability (Details Textual) - USD ($)						1 Months Ended			3 Months Ended
	Mar. 06, 2020	Aug. 08, 2019	Oct. 27, 2015	Oct. 22, 2015	Mar. 03, 2015	Jul. 31, 2019	Oct. 31, 2015	Jul. 31, 2011	Mar. 31, 2020	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2019	Oct. 09, 2019	Aug. 31, 2019	Aug. 13, 2019	May 31, 2019	Feb. 29, 2016	Jan. 05, 2012
Noncash or Part Noncash Acquisition, Noncash Financial or Equity Instrument Consideration, Warrants Issued (in shares)								139,520
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share)								$ 33.25	$ 1.11				$ 1.09
Minimum Common Stock Closing Bid Price Per Share (in dollars per share)																			$ 66.50
Stock Issued During Period, Shares, New Issues (in shares)		4,198,566								4,198,566
Shares Issued, Price Per Share (in dollars per share)		$ 1	$ 5
Class of Warrant or Right, Exercised During Period (in shares)									299,000
Proceeds from Warrant Exercises									$ 201,000
Underwriting Agreement [Member]
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share)			$ 5
Warrants and Rights Outstanding, Term (Month)			5 years
Stock Issued During Period, Shares, New Issues (in shares)			492,000
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares)			442,802
Proceeds from Issuance of Stock and Warrants			$ 2,100,000
Warrants and Rights Outstanding			$ 1,300,000
March 2015 Short-term and Long-term Warrants [Member]
Length of Notice for warrant Holders (Day)					20 days		2 days
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares)									70,000		133,167
Class of Warrant or Right, Exercised During Period (in shares)									70,000		133,167
Proceeds from Warrant Exercises									$ 14,000		$ 13,000
Short-term Warrants [Member] | Private Placement [Member]
Warrants and Rights Outstanding, Term (Month)				1 year 90 days
Long-term Warrants [Member] | Private Placement [Member]
Warrants and Rights Outstanding, Term (Month)				5 years
The 2011 and March 2015 Warrants [Member]
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share)				$ 5
Class of Warrant or Right Price Protection Provision Exchangeable Securities Exercise Price Trigger (in dollars per share)				$ 5
July 2011, March 2015, and October 2015 Warrants [Member]
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share)																	$ 0.2061	$ 1.81
The July 2011 Warrants [Member]
Class of Warrant or Right, Expired During Period (in shares)	35,107								35,107
Warrants and Rights Outstanding									$ 0
The March 2015 Warrants [Member]
Class of Warrant or Right, Expired During Period (in shares)	7,419								7,419
July 2011 and October 2015 Warrants [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares)						102,602				102,602	158,400
Warrants and Rights Outstanding										$ 200,000	$ 400,000
Class of Warrant or Right, Exercised During Period (in shares)						102,602				102,602	158,400
Proceeds from Warrant Exercises						$ 21,000				$ 21,000	$ 33,000
Embedded Derivative, No Longer Bifurcated, Amount Reclassified to Stockholders' Equity										$ 200,000	$ 400,000
The 2019 Domestic Warrants [Member]
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share)		$ 1.15													$ 1.15	$ 1.15
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares)		4,198,566													4,198,566
Warrants and Rights Outstanding		$ 3,100,000							$ 2,339,000							$ 3,100,000
The 2019 Foreign Warrants [Member]
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share)														$ 1.15	$ 1.15
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares)		2,700,000												2,700,000	2,700,000
Warrants and Rights Outstanding		$ 2,000,000							1,504,000							$ 2,000,000
The 2019 Ladenburg Warrants [Member]
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share)		$ 1.25													$ 1.25	$ 1.25
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares)															167,942
Warrants and Rights Outstanding									$ 92,000							$ 124,000