Note 11 - Income Taxes (Details Textual) - USD ($)	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Income Tax Adjustment, Accelerated Research and Development Expense	$ 1,300,000
Income Tax Adjustment, Accelerated Research and Development Expense, Percentage Change	40.00%
Deferred Tax Assets, Valuation Allowance	$ 69,874,000	$ 67,946,000
Unrecognized Tax Benefits In Deferred Tax Assets	700,000	600,000
Unrecognized Tax Benefits, Income Tax Penalties and Interest Expense (Reversal)	(75,000)	(20,000)	$ (15,000)
Unrecognized Tax Benefits	17,125,000	$ 16,569,000	$ 15,937,000	$ 15,109,000
Unrecognized Tax Benefits that Would Impact Effective Tax Rate	2,500,000
Unrecognized Tax Benefits, Interest on Income Taxes Accrued	3,200,000
Unrecognized Tax Benefits In Deferred Tax Asset Subject To Full Valuation Allowance	14,600,000
State and Local Jurisdiction [Member]
Tax Credit Carryforward, Amount	26,500,000
State and Local Jurisdiction [Member] | Internal Revenue Service (IRS) [Member]
Operating Loss Carryforwards	2,000,000
State and Local Jurisdiction [Member] | California Franchise Tax Board [Member]
Operating Loss Carryforwards	13,000,000
Domestic Tax Jurisdiction [Member]
Tax Credit Carryforward, Amount	24,700,000
Domestic Tax Jurisdiction [Member] | Internal Revenue Service (IRS) [Member]
Operating Loss Carryforwards, No Expiration	$ 900,000