Note 10 - Income Taxes (Details Textual) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Operating Loss Carryforwards, Total	$ 28,600
Deferred Tax Assets, Operating Loss Carryforwards, Total	10,880	$ 14,247
Deferred Tax Assets, Tax Credit Carryforwards, Other	7,500
Deferred Tax Assets, Tax Credit Carryforwards, Alternative Minimum Tax	1,000
Income Taxes Receivable	19,500	$ 9,600
Domestic Tax Authority [Member]
Deferred Tax Assets, Operating Loss Carryforwards, Total	$ 6,000
Domestic Tax Authority [Member] | Internal Revenue Service (IRS) [Member]
Open Tax Year	2017 2018 2019 2020
State and Local Jurisdiction [Member] | California Franchise Tax Board [Member]
Operating Loss Carryforwards, Total	$ 45,900
Deferred Tax Assets, Operating Loss Carryforwards, Total	$ 4,500
Open Tax Year	2016 2017 2018 2019 2020