Note 3 - Fair Value of Financial Instruments - Financial Assets Measured on a Recurring Basis (Details) - USD ($) $ in Thousands	Sep. 30, 2025	Dec. 31, 2024
Money Market Funds [Member]
Money market funds, Fair Value	$ 5,727	$ 16,489
Fair Value, Recurring [Member]
Total assets	25,272	42,983
Fair Value, Recurring [Member] | US Treasury Securities [Member]
Investments, Fair Value Disclosure	16,892	23,805
Fair Value, Recurring [Member] | Commercial Paper, Not Included with Cash and Cash Equivalents [Member]
Investments, Fair Value Disclosure	2,653	2,689
Fair Value, Recurring [Member] | Money Market Funds [Member]
Money market funds, Fair Value	5,727	16,489
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Total assets	5,727	16,489
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | US Treasury Securities [Member]
Investments, Fair Value Disclosure	0	0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Commercial Paper, Not Included with Cash and Cash Equivalents [Member]
Investments, Fair Value Disclosure	0	0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Money Market Funds [Member]
Money market funds, Fair Value	5,727	16,489
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Total assets	19,545	26,494
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | US Treasury Securities [Member]
Investments, Fair Value Disclosure	16,892	23,805
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Commercial Paper, Not Included with Cash and Cash Equivalents [Member]
Investments, Fair Value Disclosure	2,653	2,689
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Money Market Funds [Member]
Money market funds, Fair Value	0	0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Total assets	0	0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | US Treasury Securities [Member]
Investments, Fair Value Disclosure	0	0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Commercial Paper, Not Included with Cash and Cash Equivalents [Member]
Investments, Fair Value Disclosure	0	0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Money Market Funds [Member]
Money market funds, Fair Value	$ 0	$ 0