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Note 5 - Fair Value Measurements - Assets Measured at Fair Value on Recurring Basis (Details) - Fair Value, Recurring [Member] - USD ($) $ in Thousands | Sep. 30, 2025 | Dec. 31, 2024
--- | --- | ---
Assets, Fair Value Disclosure |  | $ 40,965 | $ 41,202
Cash and Cash Equivalents [Member] |  |  |
Assets, Fair Value Disclosure | [1] | 40,935 | 41,185
Equity Securities [Member] |  |  |
Assets, Fair Value Disclosure |  | 30 | 17
Marketable Securities [Member] |  |  |
Assets, Fair Value Disclosure |  | 30 | 17
Fair Value, Inputs, Level 1 [Member] |  |  |
Assets, Fair Value Disclosure |  | 40,965 | 41,202
Fair Value, Inputs, Level 1 [Member] | Cash and Cash Equivalents [Member] |  |  |
Assets, Fair Value Disclosure | [1] | 40,935 | 41,185
Fair Value, Inputs, Level 1 [Member] | Equity Securities [Member] |  |  |
Assets, Fair Value Disclosure |  | 30 | 17
Fair Value, Inputs, Level 1 [Member] | Marketable Securities [Member] |  |  |
Assets, Fair Value Disclosure |  | 30 | 17
Fair Value, Inputs, Level 2 [Member] |  |  |
Assets, Fair Value Disclosure | [1] | 0 | 0
Fair Value, Inputs, Level 3 [Member] |  |  |
Assets, Fair Value Disclosure | [1] | $ 0 | $ 0
[1] | As of September 30, 2025 and December 31, 2024, included investments in money market mutual funds managed or advised by GAMCO Investors, Inc.

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