v3.25.2
FAIR VALUE, Financial Instruments Measured at Fair Value on a Nonrecurring Basis (Details) - Nonrecurring
$ in Millions
 9 Months Ended 12 Months Ended
Jun. 30, 2025
USD ($)
Sep. 30, 2024
USD ($)
Loans held for sale    
Fair Value, Assets and Liabilities Measured on Nonrecurring Basis [Line Items]    
Bank loans, net $ 38  
Loans held for sale | Level 2    
Fair Value, Assets and Liabilities Measured on Nonrecurring Basis [Line Items]    
Bank loans, net 38  
Loans held for sale | Level 3    
Fair Value, Assets and Liabilities Measured on Nonrecurring Basis [Line Items]    
Bank loans, net 0  
Collateral or discounted cash flow | Bank loans - residential    
Fair Value, Assets and Liabilities Measured on Nonrecurring Basis [Line Items]    
Bank loans, net 9 $ 9
Collateral or discounted cash flow | Bank loans - residential | Level 2    
Fair Value, Assets and Liabilities Measured on Nonrecurring Basis [Line Items]    
Bank loans, net 2 2
Collateral or discounted cash flow | Bank loans - residential | Level 3    
Fair Value, Assets and Liabilities Measured on Nonrecurring Basis [Line Items]    
Bank loans, net 7 7
Collateral or discounted cash flow | Bank loans - corporate    
Fair Value, Assets and Liabilities Measured on Nonrecurring Basis [Line Items]    
Bank loans, net 132 106
Collateral or discounted cash flow | Bank loans - corporate | Level 2    
Fair Value, Assets and Liabilities Measured on Nonrecurring Basis [Line Items]    
Bank loans, net 0 0
Collateral or discounted cash flow | Bank loans - corporate | Level 3    
Fair Value, Assets and Liabilities Measured on Nonrecurring Basis [Line Items]    
Bank loans, net $ 132 $ 106
Minimum | Collateral or discounted cash flow | Bank loans - residential | Prepayment rate    
Fair Value, Assets and Liabilities Measured on Nonrecurring Basis [Line Items]    
Prepayment term (in years) 7 years 7 years
Minimum | Collateral or discounted cash flow | Bank loans - corporate | Recovery rate    
Fair Value, Assets and Liabilities Measured on Nonrecurring Basis [Line Items]    
Bank loans, net, measurement input (as a percent) 0.35 0
Maximum | Collateral or discounted cash flow | Bank loans - residential | Prepayment rate    
Fair Value, Assets and Liabilities Measured on Nonrecurring Basis [Line Items]    
Prepayment term (in years) 12 years 12 years
Maximum | Collateral or discounted cash flow | Bank loans - corporate | Recovery rate    
Fair Value, Assets and Liabilities Measured on Nonrecurring Basis [Line Items]    
Bank loans, net, measurement input (as a percent) 0.35 0.37
Weighted average | Collateral or discounted cash flow | Bank loans - residential | Prepayment rate    
Fair Value, Assets and Liabilities Measured on Nonrecurring Basis [Line Items]    
Prepayment term (in years) 10 years 6 months 10 years 6 months
Weighted average | Collateral or discounted cash flow | Bank loans - corporate | Recovery rate    
Fair Value, Assets and Liabilities Measured on Nonrecurring Basis [Line Items]    
Bank loans, net, measurement input (as a percent) 0.35 0.37