Note 13 - Subsequent Event (Details Textual) - shares	Jul. 17, 2019	Jun. 30, 2019
Class of Warrant or Right, Outstanding		10,085,474
Warrant Exchange [Member] | Subsequent Event [Member]
Warrant Exchange, Common Stock to be Received	0.385
Class of Warrant or Right, Outstanding	9,935,000
Class of Warrant or Right, Number of Securities Called by Warrants or Rights	3,824,959
Warrants Exchanged in Consent Solicitation [Member] | Subsequent Event [Member]
Non Warrant Exchange, Common Stock to be Received	0.36575
Class of Warrant or Right, Outstanding	150,474
Class of Warrant or Right, Number of Securities Called by Warrants or Rights	55,000