Note 2 - Investments - Components of Investments (Details) - USD ($)		Mar. 31, 2023		Jun. 30, 2022
Statement [Line Items]
Cost		$ 19,601,000		$ 19,967,000
Unrealized gains losses		(6,417,000)		(5,667,000)
Investments in equity securities		13,184,000		14,300,000
Amortized cost		8,006,000	[1]	8,576,000
Unrealized gains		2,100,000		4,588,000
Available-for-sale - Convertible debentures (1)		(2,457,000)		(2,539,000)
Investments in debt securities		7,649,000	[1]	10,625,000
Amortized cost, held-to-maturity	[2]	1,000,000		1,000,000
Unrecognized gains, held-to-maturity		0	[2]	0
Unrecognized losses, held-to-maturity		(245,000)	[2]	(133,000)
Fair value, held-to-maturity		755,000	[2]	867,000
Equity Securities International [Member]
Statement [Line Items]
Cost		6,679,000		6,680,000
Unrealized gains losses		(5,941,000)		(5,141,000)
Investments in equity securities		738,000		1,539,000
Equity Securities Domestic [Member]
Statement [Line Items]
Cost		45,000		45,000
Unrealized gains losses		(45,000)		(45,000)
Investments in equity securities		0		0
Mutual Funds Fixed Income [Member]
Statement [Line Items]
Cost		11,948,000		12,313,000
Unrealized gains losses		(247,000)		(175,000)
Investments in equity securities		11,701,000		12,138,000
Mutual Funds Global Equity [Member]
Statement [Line Items]
Cost		929,000		929,000
Unrealized gains losses		(184,000)		(306,000)
Investments in equity securities		$ 745,000		$ 623,000

[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, and the fair value is classified as Level 2 according to the fair value hierarchy.