Note 12 - Income Taxes (Details Textual) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Operating Loss Carryforwards, Total	$ 71,700
Deferred Tax Assets, Operating Loss Carryforwards, Subject to Expiration	7,900
Income Tax Expense (Benefit), Total	$ 0	$ 0
Open Tax Year	2015 2016 2017 2018 2019