Note 4 - Investments - Components of Investments (Details) - USD ($)		12 Months Ended
		Jun. 30, 2024		Jun. 30, 2023
Cost		$ 11,605,000		$ 19,601,000
Unrealized gains (losses)		(720,000)		(6,396,000)
Equity Securities, FV-NI		10,885,000		13,205,000
Corporate debt securities, Unrealized gains (losses)		(7,000)		0
Total trading securities at fair value, cost		11,820,000		19,601,000
Total trading securities at fair value, Unrealized gains (losses)		(727,000)		(6,396,000)
Total trading securities at fair value		11,093,000		13,205,000
Amortized cost		6,204,000	[1]	7,729,000
Debt Securities, Available-for-Sale, Total	[1]	4,414,000
Allowance for credit losses		0		0
Corporate debt securities	[2]	1,000,000		1,000,000
Corporate debt securities	[2]	132,000		0
Debt Securities, Held-to-Maturity, Amortized Cost, after Allowance for Credit Loss	[2]	868,000		1,000,000
Corporate debt securities	[2]	0		0
Corporate debt securities	[2]	0		(232,000)
Corporate debt securities	[2]	868,000		768,000
Convertible Debt Securities [Member]
Amortized cost		6,204,000		7,729,000
Gross unrealized gains in other comprehensive income (loss)		740,000		1,707,000
Gross unrealized losses in other comprehensive income (loss)		0		0
Gross unrealized losses in net investment income (loss)	[3]	(2,530,000)		(2,428,000)
Debt Securities, Available-for-Sale, Total		4,414,000		7,008,000
Allowance for credit losses		0		0
Corporate Debt Securities [Member]
Corporate debt securities, cost		215,000		0
Corporate debt securities, Unrealized gains (losses)		(7,000)		0
Corporate debt securities, fair value		208,000		0
Equity Securities International [Member]
Cost		762,000		6,679,000
Unrealized gains (losses)		(327,000)		(5,901,000)
Equity Securities, FV-NI		435,000		778,000
Equity Securities Domestic [Member]
Cost		45,000		45,000
Unrealized gains (losses)		(45,000)		(45,000)
Equity Securities, FV-NI		0		0
Mutual Funds Fixed Income [Member]
Cost		9,869,000		11,947,000
Unrealized gains (losses)		(225,000)		(305,000)
Equity Securities, FV-NI		9,644,000		11,642,000
Mutual Funds Global Equity [Member]
Cost		929,000		930,000
Unrealized gains (losses)		(123,000)		(145,000)
Equity Securities, FV-NI		$ 806,000		$ 785,000

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

[2] Held-to-maturity debt instruments 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.

[3] Represents changes in unrealized gains and losses related to embedded derivatives included in net investment income (loss) in the Consolidated Statements of Operations.