Note 3 - Investments - Components of Investments (Details) - USD ($)		3 Months Ended			6 Months Ended			12 Months Ended
		Dec. 31, 2023		Dec. 31, 2022	Dec. 31, 2023		Dec. 31, 2022	Jun. 30, 2023
Cost		$ 17,849,000			$ 17,849,000			$ 19,601,000
Unrealized gains losses		(6,552,000)			(6,552,000)
Investments in equity securities		11,297,000			11,297,000			13,205,000
Corporate debt securities		46,000		$ 0	46,000		$ 0
Total trading securities at fair value		18,064,000			18,064,000			19,601,000
Total trading securities at fair value		(6,507,000)			(6,507,000)			(6,396,000)
Total trading securities at fair value		11,557,000			11,557,000			13,205,000
Unrealized gains (losses) on equity securities		279,000		$ (937,000)	(164,000)		$ (2,868,000)	(6,396,000)
Amortized cost		7,056,000	[1]		7,056,000	[1]		7,729,000
Debt Securities, Available-for-Sale, Total	[1]	5,784,000			5,784,000
Allowance for credit losses		0			0			0
Corporate debt securities, cost		1,000,000	[2]		1,000,000	[2]		1,000,000
Corporate debt securities, gains		0	[2]		0	[2]		0
Corporate debt securities, losses		(177,000)	[2]		(177,000)	[2]		(232,000)
Corporate debt securities, fair value		823,000	[2]		823,000	[2]		768,000
Corporate debt securities		177,000	[2]		177,000	[2]		0
Convertible Debt Securities [Member]
Amortized cost		7,056,000			7,056,000			7,729,000
Gross unrealized gains in other comprehensive income (loss)		1,219,000			1,219,000			1,707,000
Gross unrealized losses in other comprehensive income (loss)		0			0			0
Gross unrealized losses in net investment income (loss)		(2,491,000)			(2,491,000)			(2,428,000)
Debt Securities, Available-for-Sale, Total		5,784,000			5,784,000			7,008,000
Allowance for credit losses		0			0			0
Corporate Debt Securities [Member]
Corporate debt securities, cost		215,000			215,000			0
Corporate debt securities					45,000
Corporate debt securities, fair value		260,000			260,000			0
Total trading securities at fair value								0
Equity Securities International [Member]
Cost		6,595,000			6,595,000			6,679,000
Unrealized gains losses		(6,150,000)			(6,150,000)
Investments in equity securities		445,000			445,000			778,000
Unrealized gains (losses) on equity securities								(5,901,000)
Equity Securities Domestic [Member]
Cost		45,000			45,000			45,000
Unrealized gains losses		(45,000)			(45,000)
Investments in equity securities		0			0			0
Unrealized gains (losses) on equity securities								(45,000)
Mutual Funds Fixed Income [Member]
Cost		10,280,000			10,280,000			11,947,000
Unrealized gains losses		(188,000)			(188,000)
Investments in equity securities		10,092,000			10,092,000			11,642,000
Unrealized gains (losses) on equity securities								(305,000)
Mutual Funds Global Equity [Member]
Cost		929,000			929,000			930,000
Unrealized gains losses		(169,000)			(169,000)
Investments in equity securities		$ 760,000			$ 760,000			785,000
Unrealized gains (losses) on equity securities								$ (145,000)

[1] Principal payments of $750,000 are due quarterly with a final maturity date in January 2026.

[2] Held-to-maturity debt investments are carried at amortized cost, net of allowance for credit losses, and the fair value is classified as Level 2 according to the fair value hierarchy.