Note 4 - Investments (Details Textual) $ / shares in Units, shares in Millions				3 Months Ended		12 Months Ended
		Jan. 12, 2021 USD ($)	Jul. 01, 2018 USD ($)	Jun. 30, 2022 USD ($) $ / shares shares		Jun. 30, 2022 USD ($) $ / shares shares		Jun. 30, 2021 USD ($) $ / shares shares	Jun. 30, 2022 $ / shares	Jun. 30, 2021 $ / shares
Investment Owned, Fair Value				$ 24,900,000		$ 24,900,000
Investment Owned, Cost				$ 28,500,000		$ 28,500,000
Value of Fair Value Investments to Company Assets, Percent				42.70%		42.70%
Equity Securities without Readily Determinable Fair Value, Amount				$ 3,992,000		$ 3,992,000		$ 3,453,000
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				14,300,000		14,300,000		18,258,000
Debt Securities, Available-for-Sale, Total	[1]			10,625,000	[2]	10,625,000	[2]	17,049,000
OCI, Debt Securities, Available-for-Sale, Unrealized Holding Gain (Loss), before Adjustment, after Tax						(1,209,000)		7,496,000
Investment Income, Net, Total						(6,174,000)		28,338,000
Equity Securities, FV-NI, Cost				19,967,000		19,967,000		14,363,000
Debt Securities, Held-to-Maturity, Accumulated Unrecognized Loss	[3]			133,000		133,000		(0)
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				1,500,000		1,500,000
Equity Securities without Readily Determinable Fair Value, Upward Price Adjustment, Annual Amount						187,000		1,561,000
Income (Loss) from Equity Method Investments						(206,000)		347,000
Equity Method Investments				0		0		532,000
Realized Gain (Loss) on Principal Payment Proceeds						2,200,000		1,200,000
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Reclassification Adjustment from AOCI, Realized upon Sale or Liquidation, Net of Tax						10,000		(0)
Equity Securities Without Readily Determinable Fair Values, Unrealized Gain (Loss)						187,000		1,400,000
U S Global Investors Funds [Member]
Investment Owned, Fair Value				12,800,000		12,800,000		7,300,000
HIVE Blockchain Technologies Ltd. [Member]
Investment Owned, Fair Value				11,100,000		11,100,000		25,100,000
Equity Securities, FV-NI, Cost								2,400,000
Proceeds from Sale of Long-Term Investments								20,600,000
Equity Securities, FV-NI, Realized Gain								15,000,000.0
Realized Gain (Loss) on Principal Payment Proceeds						2,200,000		1,200,000
HIVE Blockchain Technologies Ltd. [Member] | Convertible Securities [Member]
Investment Owned, Balance, Principal Amount		$ 15,000,000.0		10,600,000		10,600,000
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, Fair Value				11,100,000		11,100,000		25,100,000
HIVE Blockchain Technologies Ltd. [Member] | Unsecured Convertible Debentures [Member]
Debt Securities, Available-for-Sale, Total		16,000,000.0		$ 10,600,000		$ 10,600,000		$ 17,000,000.0
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		$ 11.70		$ 2.34
Investment Income, Net, Total						$ 2,200,000		$ 1,200,000
HIVE Blockchain Technologies Ltd. [Member] | Common Shares Purchase Warrants [Member]
Investment, Common Share Purchase Warrants (in shares) | shares				5		5		5
Class of Warrant or Right, Exercise Price of Warrants or Rights (in CAD per share) | $ / shares									$ 15.00	$ 3.00
Equity Securities, FV-NI, Total		$ 5,900,000		$ 515,000		$ 515,000		$ 8,000,000.0
HIVE Blockchain Technologies Ltd. [Member] | Common Shares [Member]
Equity Securities, FV-NI, Cost								2,400,000
Equity Securities, FV-NI, Realized Gain								$ 15,000,000.0
HIVE Blockchain Technologies Ltd. [Member] | Common Shares [Member] | Equity Securities [Member]
Investment Owned, Balance, Shares (in shares) | shares								10
Reclassification from AOCI, Current Period, before Tax, Attributable to Parent			$ 3,200,000					$ 3,200,000
Proceeds from Sale of Long-Term Investments								20,600,000
Thunderbird Entertainment Group [Member]
Equity Securities, FV-NI, Total								2,700,000
Equity Securities, FV-NI, Realized Gain						1,900,000		$ 936,000
Thunderbird Entertainment Group [Member] | Equity Securities [Member]
Investment Owned, Direct Percentage								1.60%
Thunderbird Entertainment Group [Member] | Fair Value, Inputs, Level 1 [Member]
Equity Securities, FV-NI, Current								$ 2,700,000
Gold Spot Discoveries Inc [Member]
Equity Securities, FV-NI, Realized Gain								600,000
The Sonar Company [Member]
Equity Securities without Readily Determinable Fair Value, Amount				$ 362,000		$ 362,000		$ 100,000
Investment Owned, Direct Percentage				3.70%		3.70%
Other Investments and Securities, at Cost				$ 175,000		$ 175,000
Equity Securities without Readily Determinable Fair Value, Upward Price Adjustment, Annual Amount						187,000
Galileo New Economy Fund L P [Member]
Equity Method Investment, Ownership Percentage								22.00%
Income (Loss) from Equity Method Investments						(206,000)		$ 347,000
Equity Method Investments								532,000
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] Changes in unrealized gains and losses are included in the statement of comprehensive income (loss), except for embedded derivatives. Changes in unrealized and realized gains and losses for embedded derivatives are included in earnings in the statement of operations.

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

[3] Held-to-maturity debt instruments are carried at amortized cost, and the fair value is classified as Level 2 according to the fair value hierarchy.