Note 2 - Investments (Details Textual)	3 Months Ended				6 Months Ended
	Dec. 31, 2022 USD ($) $ / shares shares		Dec. 31, 2021 USD ($)	Mar. 31, 2021 USD ($) $ / shares	Dec. 31, 2022 USD ($) $ / shares shares		Jun. 30, 2022 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2022 $ / shares	Sep. 30, 2021	Mar. 31, 2021 $ / shares
Investment Owned, at Fair Value	$ 21,400,000				$ 21,400,000
Investment Owned, at Cost	$ 28,200,000				$ 28,200,000
Value of Fair Value Investments to Company Assets, Percent	38.90%				38.90%
Equity Securities without Readily Determinable Fair Value, Amount	$ 2,633,000		$ 3,551,000		$ 2,633,000		$ 3,992,000	$ 3,551,000
Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss, Total	1,000,000.0				1,000,000.0		1,000,000.0
Equity Securities, FV-NI, Total	13,264,000				13,264,000		14,300,000
Debt Securities, Available-for-Sale, Total	8,127,000	[1]			8,127,000	[1]	10,625,000
OCI, Debt Securities, Available-for-Sale, Unrealized Holding Gain (Loss), before Adjustment, after Tax	(904,000)		(140,000)		(1,019,000)			(287,000)
Investment Income, Net, Total	116,000		1,579,000		(1,344,000)			1,545,000
Debt Securities, Held-to-Maturity, Accumulated Unrecognized Loss	251,000	[2]			251,000	[2]	133,000
Debt Securities, Available-for-Sale, Periodic Principal Payments					750,000
Equity Securities without Readily Determinable Fair Value, Upward Price Adjustment, Cumulative Amount	2,500,000				2,500,000
Equity Securities without Readily Determinable Fair Value, Downward Price Adjustment, Cumulative Amount	3,300,000				3,300,000
Income (Loss) from Equity Method Investments	0		(48,000)		0			(33,000)
Realized Gain (Loss) on Principal Payment Proceeds	436,000		569,000		905,000			1,200,000
Equity Securities Without Readily Determinable Fair Values, Unrealized Gain (Loss)	5,000		0		1,800,000			0
U S Global Investors Funds [Member]
Investment Owned, at Fair Value	12,600,000				12,600,000		12,800,000
HIVE Blockchain Technologies Ltd. [Member] | Convertible Securities [Member]
Investment Owned, Balance, Principal Amount				$ 15,000,000.0
HIVE Blockchain Technologies Ltd. [Member] | Warrants and Convertible Debentures [Member] | Fair Value, Inputs, Level 3 [Member] | Available-for-sale Securities and Equity Securities [Member]
Investment Owned, at Fair Value	8,200,000				8,200,000		11,100,000
HIVE Blockchain Technologies Ltd. [Member] | Unsecured Convertible Debentures [Member]
Debt Securities, Available-for-Sale, Total	$ 8,100,000			16,000,000.0	$ 8,100,000		10,600,000
OCI, Debt Securities, Available-for-Sale, Unrealized Holding Gain (Loss), before Adjustment, after Tax				$ 6,900,000
HIVE Blockchain Technologies Ltd. [Member] | Unsecured Convertible Debentures [Member] | Convertible Debt Securities [Member]
Debt Instrument, Interest Rate, Stated Percentage				8.00%
Debt Instrument, Convertible, Conversion Price (in dollars per share) | $ / shares	$ 11.70			$ 2.34	$ 11.70
Investment Income, Net, Total	$ 436,000		569,000		$ 905,000			1,200,000
HIVE Blockchain Technologies Ltd. [Member] | Common Shares Purchase Warrants [Member]
Investment, Common Share Purchase Warrants (in shares) | shares	5,000,000				5,000,000
Class of Warrant or Right, Exercise Price of Warrants or Rights (in CAD per share) | $ / shares									$ 15.00		$ 3.00
Class of Warrant or Right, Number of Securities Called by Each Warrant or Right (in shares) | shares	5				5
Equity Securities, FV-NI, Total	$ 26,000			$ 5,900,000	$ 26,000		515,000,000,000
HIVE Blockchain Technologies Ltd. [Member] | Convertible Securities [Member]
Investment Owned, Balance, Principal Amount	9,100,000				9,100,000
Thunderbird Entertainment Group [Member]
Equity Securities, FV-NI, Realized Gain			43,000					1,900,000
The Sonar Company [Member]
Equity Securities without Readily Determinable Fair Value, Amount	362,000				362,000
Other Investments and Securities, at Cost	$ 175,000				$ 175,000
Investment Owned, Direct Percentage	2.80%				2.80%
Galileo New Economy Fund L P [Member]
Equity Method Investment, Ownership Percentage										22.00%
Income (Loss) from Equity Method Investments			$ 48,000					$ 33,000
Galileo New Economy Fund L P [Member] | Cash [Member]
Proceeds from Equity Method Investment, Distribution, Return of Capital							85,000
Galileo New Economy Fund L P [Member] | Common Shares [Member]
Proceeds from Equity Method Investment, Distribution, Return of Capital							$ 228,000

[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.