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Note 9 - Investments in Marketable Securities - Marketable Securities and Restricted Marketable Securities (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Unrestricted investments available for sale, equity, amortized cost	$ 24,734	$ 24,734
Marketable equity securities	133,317	111,117
Unrestricted investments available for sale, debt, amortized cost	126,461	135,338
Unrestricted investments available for sale, debt, fair value	119,795	127,727
Restricted marketable equity securities	21,566	26,779
Investments available for sale, amortized cost	174,234	189,648
Marketable Securities	274,678	265,623
Equity Securities [Member]
Unrestricted investments available for sale, equity, amortized cost	30,176	30,176
Marketable equity securities	133,317	111,117
Restricted investments available for sale, equity, amortized cost	17,597	24,134
Restricted marketable equity securities	21,566	26,779
Corporate Debt Securities [Member]
Unrestricted investments available for sale, debt, amortized cost	494	2,497
Unrestricted investments available for sale, debt, fair value	488	2,441
Restricted investments available for sale, debt, amortized cost	57,688	59,586
Restricted investments available for sale, debt, fair value	55,536	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	46,019	46,771
Restricted investments available for sale, debt, fair value	43,094	42,863
Asset-Backed Securities [Member]
Restricted investments available for sale, debt, amortized cost	18,421	19,388
Restricted investments available for sale, debt, fair value	16,924	17,659
US States and Political Subdivisions Debt Securities [Member]
Restricted investments available for sale, debt, amortized cost	3,839	4,106
Restricted investments available for sale, debt, fair value	$ 3,753	$ 4,047

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