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Note 10 - Investments in Marketable Securities - Marketable Securities and Restricted Marketable Securities (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Unrestricted investments available for sale, equity, amortized cost	$ 24,734	$ 24,734
Marketable equity securities	164,754	111,117
Unrestricted investments available for sale, debt, amortized cost	127,060	135,338
Unrestricted investments available for sale, debt, fair value	123,911	127,727
Restricted marketable equity securities	23,001	26,779
Investments available for sale, amortized cost	174,938	189,648
Marketable Securities	311,666	265,623
Equity Securities [Member]
Unrestricted investments available for sale, equity, amortized cost	30,176	30,176
Marketable equity securities	164,754	111,117
Restricted investments available for sale, equity, amortized cost	17,702	24,134
Restricted marketable equity securities	23,001	26,779
Corporate Debt Securities [Member]
Unrestricted investments available for sale, debt, amortized cost	0	2,497
Unrestricted investments available for sale, debt, fair value	0	2,441
Restricted investments available for sale, debt, amortized cost	59,267	59,586
Restricted investments available for sale, debt, fair value	58,812	57,731
US Government Corporations and Agencies Securities [Member]
Unrestricted investments available for sale, debt, amortized cost	0	2,990
Unrestricted investments available for sale, debt, fair value	0	2,986
Restricted investments available for sale, debt, amortized cost	46,224	46,771
Restricted investments available for sale, debt, fair value	44,671	42,863
Asset-Backed Securities [Member]
Restricted investments available for sale, debt, amortized cost	17,756	19,388
Restricted investments available for sale, debt, fair value	16,646	17,659
US States and Political Subdivisions Debt Securities [Member]
Restricted investments available for sale, debt, amortized cost	3,813	4,106
Restricted investments available for sale, debt, fair value	$ 3,782	$ 4,047

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