Note 6 - Non-operating Income - Summary of Non-operating Income (Details) - USD ($)	1 Months Ended	3 Months Ended		9 Months Ended
	Jan. 31, 2024	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Dividends and net realized gains and losses on sales of securities		$ 1,683,000	$ 1,690,000	$ 5,462,000	$ 4,604,000
Interest income		2,603,000	2,222,000	7,790,000	5,571,000
Equity in earnings of unconsolidated investments		(62,000)	185,000	589,000	1,941,000
Gain on sale of unconsolidated company	$ 1,024,000	0	0	1,024,000	(0)
Total non-operating income		$ 4,224,000	$ 4,097,000	$ 14,865,000	$ 12,116,000