Note 10 - Income Taxes (Details Textual) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Operating Loss Carryforwards, Total	$ 43,000
Deferred Tax Assets, Operating Loss Carryforwards, Total	14,247	$ 17,098
Deferred Tax Assets, Tax Credit Carryforwards, Other	7,700
Deferred Tax Assets, Tax Credit Carryforwards, Alternative Minimum Tax	1,100
Income Taxes Receivable	9,600	$ 9,000
Domestic Tax Authority [Member]
Deferred Tax Assets, Operating Loss Carryforwards, Total	9,000
State and Local Jurisdiction [Member] | California Franchise Tax Board [Member]
Operating Loss Carryforwards, Total	52,800
Deferred Tax Assets, Operating Loss Carryforwards, Total	$ 5,200