Note 4 - Income Taxes (Details Textual) $ in Thousands	6 Months Ended
	Jun. 30, 2019 USD ($)
Unrecognized Tax Benefits, Ending Balance	$ 1,800
Deferred Tax Assets, Net, Total	0
Domestic Tax Authority [Member] | Internal Revenue Service (IRS) [Member]
Operating Loss Carryforwards, Total	$ 321,000
Open Tax Year	2015 2016 2017 2018
Open Tax Period	3 years
State and Local Jurisdiction [Member] | California Franchise Tax Board [Member]
Operating Loss Carryforwards, Total	$ 201,000
Open Tax Year	2014 2015 2016 2017 2018
Open Tax Period	4 years