Note 2 - Investments (Details Textual) - USD ($)	3 Months Ended						9 Months Ended		12 Months Ended
	Jan. 31, 2024	Oct. 31, 2023	Jul. 31, 2023	Jan. 31, 2023	Oct. 31, 2022	Jul. 31, 2022	Jan. 31, 2024	Jan. 31, 2023	Apr. 30, 2023
Equity Securities, FV-NI, Cost	$ 11,109,000						$ 11,109,000		$ 10,169,000
Equity Securities, FV-NI	15,370,000						15,370,000		14,546,000
Proceeds from Sale of Equity Securities, FV-NI							1,129,000	$ 1,421,000
Other Comprehensive Income (Loss), Available-for-Sale Securities Adjustment, Net of Tax, Portion Attributable to Parent	258,000	$ (448,000)	$ (212,000)	$ 123,000	$ (3,000)	$ 5,000	(402,000)	125,000
OCI, Debt Securities, Available-for-Sale, Unrealized Holding Gain (Loss), before Adjustment, Tax							(106,000)	33,000
Equity Securities, FV-NI, Gain (Loss)							(16,000)	(2,000)
Equity Method Investments	59,640,000						59,640,000		58,775,000
EAM Trust [Member]
Fair Value of Contributed Capital at Inception	55,805,000						55,805,000		55,805,000
Cash and Liquid Securities in Excess of Working Capital Requirements Contributed to Capital Account	5,820,000						$ 5,820,000		5,820,000
Percentage of Non Voting Profit Interest							50.00%
Accrued Non Voting Revenues and Non Voting Profits Interests Payable	3,448,000						$ 3,448,000		2,601,000
Equity Method Investment, Other than Temporary Impairment							0		0
Fixed Income Securities [Member]
Proceeds from Sale and Maturity of Debt Securities, Available-for-Sale							32,113,000	$ 9,907,000
AOCI, Debt Securities, Available-for-Sale, Adjustment, after Tax	$ 34,000						34,000		473,000
Other Comprehensive Income (Loss), Available-for-Sale Securities Adjustment, Net of Tax, Portion Attributable to Parent							508,000		503,000
OCI, Debt Securities, Available-for-Sale, Unrealized Holding Gain (Loss), before Adjustment, Tax							$ 106,000		$ 105,000
Debt Securities, Available-for-Sale, Weighted Average Yield	4.56%						4.56%		2.55%
Fixed Income Securities [Member] | AOCI, Accumulated Gain (Loss), Debt Securities, Available-for-Sale, Parent [Member]
AOCI Tax, Attributable to Parent	$ 6,000						$ 6,000		$ 99,000