v3.25.2
Transactions with Controlled Companies - Valley Electric Company, Inc. (Details) - USD ($)
$ in Thousands
 12 Months Ended
Jun. 30, 2025
Jun. 30, 2024
Jun. 30, 2023
Subsidiary of Limited Liability Company or Limited Partnership [Line Items]      
Interest Income $ 671,109 $ 770,312 $ 760,785
Dividend Income 19,378 11,953 8,405
Structuring Fee 12,348 27,666 18,131
Total Other Income 28,949 79,397 83,023
Interest Receivable $ 25,144 $ 26,936  
Valley Electric Holdings II, Inc. | Valley Electric Holdings I, Inc.      
Subsidiary of Limited Liability Company or Limited Partnership [Line Items]      
Ownership interest 100.00% 100.00%  
Valley Electric Company, Inc. | Members of Valley Electric Company, Inc.      
Subsidiary of Limited Liability Company or Limited Partnership [Line Items]      
Ownership interest 5.01%    
Valley Electric Company, Inc. | Valley Electric Holdings II, Inc.      
Subsidiary of Limited Liability Company or Limited Partnership [Line Items]      
Ownership interest 94.99% 94.99%  
VE Company, Inc. | Valley Electric Company, Inc.      
Subsidiary of Limited Liability Company or Limited Partnership [Line Items]      
Ownership interest 100.00% 100.00%  
Valley Electric Co. of Mt. Vernon, Inc. | VE Company, Inc.      
Subsidiary of Limited Liability Company or Limited Partnership [Line Items]      
Ownership interest 100.00% 100.00%  
Reportable Legal Entities | Subsidiaries | Valley Electric Company, Inc.      
Subsidiary of Limited Liability Company or Limited Partnership [Line Items]      
Interest Income $ 12,677 $ 12,316 9,403
Dividend Income 0 0 547
Structuring Fee 0 0 380
Royalty, net profit and revenue interests 666 666 666
Total Other Income 666 666 1,046
Additions 0 0 19,000
Interest Income Capitalized as PIK 0 4,763 3,341
Repayment of Loan Receivable 0 0 (548)
Interest Receivable 757 2,974  
Other Receivables 9 2  
Reportable Legal Entities | Subsidiaries | Valley Electric Company, Inc. | Prospect Administration      
Subsidiary of Limited Liability Company or Limited Partnership [Line Items]      
Managerial Assistance 600 600 600
Reimbursement of Legal, Tax, etc $ 3 $ 0 85
Reportable Legal Entities | Subsidiaries | Valley Electric Holdings I, Inc.      
Subsidiary of Limited Liability Company or Limited Partnership [Line Items]      
Ownership interest 100.00% 100.00%  
Reportable Legal Entities | Subsidiaries | Valley Electric Company, Inc. | Valley Electric Company, Inc.      
Subsidiary of Limited Liability Company or Limited Partnership [Line Items]      
Interest Income $ 11,363 $ 10,927 7,895
Reportable Legal Entities | Subsidiaries | Valley Electric Co. of Mt. Vernon, Inc. | Valley Electric Company, Inc.      
Subsidiary of Limited Liability Company or Limited Partnership [Line Items]      
Interest Income $ 1,314 $ 1,389 $ 1,508