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Note 9 - Investments in Marketable Securities - Marketable Securities and Restricted Marketable Securities (Details) - USD ($) $ in Thousands | Mar. 31, 2025 | Dec. 31, 2024
--- | --- | ---
Unrestricted investments available for sale, equity, amortized cost | $ 24,734 | $ 24,734
Marketable equity securities | 152,785 | 140,064
Restricted marketable equity securities | 21,697 | 23,190
Unrestricted investments available for sale, debt, amortized cost | 123,888 | 125,118
Unrestricted investments available for sale, debt, fair value | 120,167 | 119,804
Investments available for sale, amortized cost | 172,843 | 173,828
Marketable Securities | 294,649 | 283,058
Equity Securities [Member] |  |
Unrestricted investments available for sale, equity, amortized cost | 30,176 | 30,176
Marketable equity securities | 152,785 | 140,064
Restricted investments available for sale, equity, amortized cost | 18,779 | 18,534
Restricted marketable equity securities | 21,697 | 23,190
Corporate Debt Securities [Member] |  |
Unrestricted investments available for sale, debt, amortized cost | 58,006 | 58,927
Unrestricted investments available for sale, debt, fair value | 57,223 | 57,471
Restricted investments available for sale, debt, amortized cost | 15,306 | 15,593
Restricted investments available for sale, debt, fair value | 14,263 | 14,410
US Government Corporations and Agencies Securities [Member] |  |
Unrestricted investments available for sale, debt, amortized cost | 46,814 | 46,811
Unrestricted investments available for sale, debt, fair value | 44,952 | 44,186
US States and Political Subdivisions Debt Securities [Member] |  |
Restricted investments available for sale, debt, amortized cost | 3,762 | 3,787
Restricted investments available for sale, debt, fair value | $ 3,729 | $ 3,737

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