Note 3 - Investments - Securities Measured and Carried at Fair Value on Recurring Basis With Significant Unobservable Inputs (Details) $ in Thousands	Sep. 30, 2023 USD ($)		Jun. 30, 2023 USD ($)
Investments in equity securities	$ 11,920		$ 13,205
Investments in debt securities	6,343	[1]	$ 7,008
Valuation Technique, Option Pricing Model [Member]
Investments in equity securities	$ 4
Valuation Technique, Option Pricing Model [Member] | Measurement Input, Price Volatility [Member]
Investments in debt securities, unobservable input	0.90
Valuation Technique, Option Pricing Model [Member] | Measurement Input, Risk Free Interest Rate [Member]
Investments in debt securities, unobservable input	0.051
Valuation Technique, Binomial Lattice Model [Member]
Investments in debt securities	$ 6,343
Valuation Technique, Binomial Lattice Model [Member] | Measurement Input, Price Volatility [Member]
Investments in debt securities, unobservable input	0.90
Valuation Technique, Binomial Lattice Model [Member] | Measurement Input, Risk Free Interest Rate [Member]
Investments in debt securities, unobservable input	0.047
Valuation Technique, Binomial Lattice Model [Member] | Measurement Input, Credit Spread [Member]
Investments in debt securities, unobservable input	0.104

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