Note 3 - Investments (Details Textual) - USD ($)		1 Months Ended	12 Months Ended
	Jan. 12, 2021	Dec. 31, 2025	Jun. 30, 2026	Jun. 30, 2025	Mar. 31, 2026	Mar. 31, 2021	Jan. 31, 2021
Debt Securities, Available-for-Sale, Total					$ 0
OCI, Debt Securities, Available-for-Sale, Unrealized Holding Gain (Loss), before Adjustment, after Tax			$ (13,000)	$ (4,000)
Debt Securities, Available-for-Sale, Realized Loss		$ 2,500,000
Debt Securities, Held-to-Maturity, Allowance for Credit Loss, Period Increase (Decrease)			24,000	80,000
Interest Receivable			25,000	40,000
Equity Securities without Readily Determinable Fair Value, Upward Price Adjustment, Cumulative Amount			5,800,000
Equity Securities without Readily Determinable Fair Value, Downward Price Adjustment, Cumulative Amount			5,500,000
Realized Gain (Loss) on Principal Payment Proceeds			108,000	610,000
Equity Securities Without Readily Determinable Fair Values, Unrealized Gain (Loss)			3,200,000	(362,000)
U S Global Investors Funds [Member]
Investment Owned, Fair Value			9,700,000	10,500,000
HIVE Blockchain Technologies Ltd. [Member]
Investment Owned, Fair Value			$ 55,000	27,000
Investment Owned, Balance, Shares (in shares)			15,000
HIVE Blockchain Technologies Ltd. [Member] | Unsecured Convertible Debentures [Member]
Debt Securities, Available-for-Sale, Total				1,600,000
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] | Estimate of Fair Value Measurement [Member]
Debt Securities, Available-for-Sale, Total	$ 16,000,000
HIVE Blockchain Technologies Ltd. [Member] | Common Shares Purchase Warrants [Member]
Investment, Common Share Purchase Warrants (in shares)						5,000,000
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share)							$ 3
HIVE Blockchain Technologies Ltd. [Member] | Common Stock [Member]
Investment Owned, Net Assets, Percentage			1.00%
HIVE Blockchain Technologies Ltd. [Member] | Common Stock [Member] | Fair Value, Inputs, Level 1 [Member]
Investment Owned, Fair Value			$ 55,000	$ 27,000
Investment Owned, Balance, Shares (in shares)			15,000
Investment Owned, Cost			$ 41,000
HIVE Blockchain Technologies Ltd. [Member] | Convertible Securities [Member]
Investment Owned, Balance, Principal Amount							$ 15,000,000
HIVE Blockchain Technologies Ltd. [Member] | Convertible Debt Securities [Member] | Unsecured Convertible Debentures [Member]
Debt Instrument, Interest Rate, Stated Percentage						8.00%
Debt Instrument, Convertible, Conversion Price (in dollars per share)					$ 11.7		$ 2.34