Note 11 - Income Taxes - Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Tax credits	$ 37,518	$ 32,037
Stock-based compensation	3,404	2,900
Deferred compensation	11,126	9,844
Net operating losses	12,115	9,000
Other expenses not currently deductible	7,755	8,891
Deferred tax assets, gross	71,918	62,672
Valuation allowance	(35,008)	(20,321)
Deferred tax assets, net of valuation allowance	36,910	42,351
Depreciation and amortization	(6,420)	(5,927)
Undistributed foreign earnings	(817)	(358)
Other expenses currently deductible	(1,619)	(814)
Deferred tax liabilities	(8,856)	(7,099)
Net deferred tax assets	$ 28,054	$ 35,252