v3.26.1
Note 3 - Related Party Transactions (Details Textual) - USD ($)
12 Months Ended
Apr. 30, 2026
Apr. 30, 2025
Apr. 30, 2024
Ownership Percentage By Parent 91.98%    
AB and Co [Member]      
Accounts Receivable, after Allowance for Credit Loss $ 0 $ 0  
Income Taxes Paid 5,200,000 5,058,000 $ 5,448,000
Reimbursement for Payments and Services [Member] | AB and Co [Member]      
Related Party Transaction, Amounts of Transaction 348,000 356,000  
EAM Trust [Member]      
Assets under Management, Carrying Amount 3,720,000,000 4,680,000,000  
Increase (Decrease) in Assets under Management $ 960,000,000    
Percentage of Assets Increased (Decreased) in Unconsolidated Entities (20.40%)    
Non Voting Profits Interest Percent 50.00%    
Percentage of Non Voting Profits Interests Due from Ex Subsidiary Payable to Parent under Agreement 90.00%    
Non Voting Profits Interest in Variable Entity Not yet Paid $ 3,885,000 $ 4,493,000  
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%