v3.26.3
Loans - Additional Information - Credit Concentration (Details)
$ in Thousands
3 Months Ended 12 Months Ended
Aug. 31, 2026
USD ($)
borrower
state
loan
distribution_system
power_supply_system
May 31, 2026
USD ($)
borrower
distribution_system
state
power_supply_system
Aug. 31, 2025
USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]      
Loans to members $ 38,337,318 $ 38,422,128 $ 37,569,601
Number of active borrowers | borrower 896 903  
Number of states with active borrowers | state 49 49  
Loans | Geographic Concentration Risk | TEXAS      
Accounts, Notes, Loans and Financing Receivable [Line Items]      
Loans to members $ 6,359,000 $ 6,403,000  
Concentration risk, percentage 17.00% 17.00%  
Number of active borrowers | borrower 66 67  
Power supply      
Accounts, Notes, Loans and Financing Receivable [Line Items]      
Number of active borrowers | borrower 49 50  
Loans Receivable Commercial And Industrial | Loans | Customer Concentration Risk | Twenty Largest Borrowers      
Accounts, Notes, Loans and Financing Receivable [Line Items]      
Loans to members $ 7,301,000 $ 7,374,000  
Concentration risk, percentage 19.00% 19.00%  
Concentration risk, number of borrowers | borrower 20 20  
Loans Receivable Commercial And Industrial | Loans | Customer Concentration Risk | Largest Single Borrower Or Controlled Group      
Accounts, Notes, Loans and Financing Receivable [Line Items]      
Concentration risk, percentage 1.00% 1.00%  
Loans Receivable Commercial And Industrial | Electric | Loans | Credit Concentration Risk      
Accounts, Notes, Loans and Financing Receivable [Line Items]      
Loans to members $ 37,732,000 $ 37,821,000  
Loans Receivable Commercial And Industrial | Distribution | Loans | Customer Concentration Risk | Twenty Largest Borrowers      
Accounts, Notes, Loans and Financing Receivable [Line Items]      
Concentration risk, number of borrowers | distribution_system 13 12  
Loans Receivable Commercial And Industrial | Power supply | Loans | Customer Concentration Risk | Twenty Largest Borrowers      
Accounts, Notes, Loans and Financing Receivable [Line Items]      
Concentration risk, number of borrowers | power_supply_system 7 8  
Loans and Finance Receivables | Loans | Credit Concentration Risk      
Accounts, Notes, Loans and Financing Receivable [Line Items]      
Concentration risk, percentage 98.00% 98.00%  
Loans Guaranteed By Rural Utilities Service      
Accounts, Notes, Loans and Financing Receivable [Line Items]      
Loans to members $ 92,000 $ 95,000  
Loans Guaranteed By Farmer Mac      
Accounts, Notes, Loans and Financing Receivable [Line Items]      
Loans to members $ 315,000 322,000  
Number of loans that defaulted | loan 0    
Number of defaulted loans put to Farmer Mac for purchase | loan 0    
Loans Guaranteed By Farmer Mac | Loans | Credit Concentration Risk | Twenty Largest Borrowers      
Accounts, Notes, Loans and Financing Receivable [Line Items]      
Loans to members $ 210,000 $ 214,000  
Concentration risk, number of borrowers | borrower 20 20  
Loans Guaranteed By Farmer Mac | Loans | Customer Concentration Risk | Twenty Largest Borrowers      
Accounts, Notes, Loans and Financing Receivable [Line Items]      
Loans to members $ 7,091,000 $ 7,160,000  
Concentration risk, number of borrowers | borrower 20 20  
Loans Guaranteed By Farmer Mac | Loans | Geographic Concentration Risk | TEXAS      
Accounts, Notes, Loans and Financing Receivable [Line Items]      
Loans to members $ 107,000 $ 109,000  
Loans receivable commercial and industrial not covered by Farmer Mac standby repurchase agreement | Loans | Geographic Concentration Risk | TEXAS      
Accounts, Notes, Loans and Financing Receivable [Line Items]      
Loans to members $ 6,252,000 $ 6,294,000