Note 12 - Fair Value Measurements (Details Textual) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Warrants and Rights Outstanding	$ 1,474	$ 1,951
Monte Carlo Model [Member] | Series K Warrants [Member] | Fair Value, Inputs, Level 3 [Member]
Warrants and Rights Outstanding	1,500
Convertible 2020 Notes [Member]
Embedded Derivative, Fair Value of Embedded Derivative, Net, Total	$ 2,400	$ 5,200