Note 1 - Summary of Significant Accounting Policies - Fair Value Measurements Using Significant Level III Inputs (Details) - Warrants [Member] - Fair Value, Inputs, Level 3 [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Balance	$ 30	$ 5,307
Issuance (exercise) of warrants, net		2,674
Change in fair value	56	(1,778)
Write off of warrants		(6,173)
Balance	$ 86	$ 30