Note 8 - Income Taxes - Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Net operating loss carryforwards	$ 12,481	$ 14,579
Tax credit carryforwards	2,070	1,907
Intangible assets	1,352	1,283
Accrued expenses, reserves and other	2,176	2,265
Research and development	984	0
Total deferred tax assets	19,063	20,034
Valuation allowance for deferred tax assets	(1,942)	(1,942)
Net deferred tax assets	17,121	18,092
Property, plant and equipment	(262)	(342)
Intangible assets	5,538	5,087
Total deferred tax liabilities	(5,800)	(5,429)
Net deferred tax assets	$ 11,321	$ 12,663