Note 3 - Investments (Details Textual)	3 Months Ended				12 Months Ended
	Sep. 30, 2022 USD ($) $ / shares shares		Sep. 30, 2021 USD ($) shares	Mar. 31, 2021 USD ($) $ / shares	Jun. 30, 2022 USD ($)	Sep. 30, 2022 $ / shares	Mar. 31, 2021 $ / shares
Investment Owned, Fair Value	$ 24,100,000
Investment Owned, at Cost	$ 28,400,000
Value of Fair Value Investments to Company Assets, Percent	42.20%
Equity Securities without Readily Determinable Fair Value, Amount	$ 2,630,000		$ 3,453,000		$ 3,992,000
Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss, Total	1,000,000.0
Equity Securities, FV-NI, Total	14,206,000				14,300,000
Debt Securities, Available-for-Sale, Total	9,866,000	[1]			10,625,000
OCI, Debt Securities, Available-for-Sale, Unrealized Holding Gain (Loss), before Adjustment, after Tax	(115,000)		(147,000)
Investment Income, Net, Total	(1,460,000)		(34,000)
Debt Securities, Held-to-Maturity, Accumulated Unrecognized Loss	202,000	[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				4,000,000.0
Equity Securities without Readily Determinable Fair Value, Downward Price Adjustment, Cumulative Amount	3,300,000
Income (Loss) from Equity Method Investments	0		15,000
Realized Gain (Loss) on Principal Payment Proceeds	469,000		602,000
Equity Securities Without Readily Determinable Fair Values, Unrealized Gain (Loss)	1,800,000		0
U S Global Investors Funds [Member]
Investment Owned, Fair Value	12,600,000				12,800,000
HIVE Blockchain Technologies Ltd. [Member] | Convertible Securities [Member]
Investment Owned, Balance, Principal Amount	9,800,000			$ 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, Fair Value	10,400,000				11,100,000
HIVE Blockchain Technologies Ltd. [Member] | Unsecured Convertible Debentures [Member]
Debt Securities, Available-for-Sale, Total	$ 9,900,000			16,000,000.0	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
Investment Income, Net, Total	$ 469,000		$ 602,000
HIVE Blockchain Technologies Ltd. [Member] | Common Shares Purchase Warrants [Member]
Investment, Common Share Purchase Warrants (in shares) | shares	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
Equity Securities, FV-NI, Total	$ 535,000			$ 5,900,000	515,000
Thunderbird Entertainment Group [Member]
Equity Securities, Shares Sold (in shares) | shares			779,000
Equity Securities, FV-NI, Realized Gain			$ 1,800,000
The Sonar Company [Member]
Equity Securities without Readily Determinable Fair Value, Amount	362,000
Other Investments and Securities, at Cost	$ 175,000
Investment Owned, Direct Percentage	2.80%
Galileo New Economy Fund L P [Member]
Equity Method Investment, Ownership Percentage			22.00%
Income (Loss) from Equity Method Investments			$ 15,000
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.