Note 7 - Related Party Transactions (Details Textual) - USD ($)	9 Months Ended		12 Months Ended
	Jan. 31, 2025	Jan. 31, 2024	Jan. 31, 2025	Apr. 30, 2024
Ownership Percentage By Parent	91.69%		91.69%
AB&Co [Member]
Increase (Decrease) in Accounts Receivable, Related Parties	$ 0		$ 0	$ 0
Income Taxes Paid	3,958,000	$ 4,000,000
AB&Co [Member] | Reimbursement for Payments and Services [Member]
Related Party Transaction, Amounts of Transaction	226,000	230,000
EAM Trust [Member]
Assets under Management, Carrying Amount	$ 4,970,000,000	$ 4,060,000,000.00	$ 4,970,000,000
Percentage of Assets Increased (Decreased) in Unconsolidated Entities			22.60%
Non Voting Revenues Interest Percent	50.00%
Non Voting Profits Interest Percent	50.00%
Accrued Investment Income Receivable	$ 4,855,000		$ 4,855,000
EAM Trust [Member] | Minimum [Member]
Non Voting Revenues Interest Percent	41.00%
Percentage of Non Voting Profits Interests Due from Ex Subsidiary Payable to Parent under Agreement	90.00%
EAM Trust [Member] | Maximum [Member]
Non Voting Revenues Interest Percent	55.00%