FAIR VALUE, Financial Instruments Measured at Fair Value on a Nonrecurring Basis (Details) - Nonrecurring $ in Millions	3 Months Ended	9 Months Ended
	Dec. 31, 2023	Jun. 30, 2024 USD ($)	Sep. 30, 2023 USD ($)
Loans held for sale
Fair Value, Assets and Liabilities Measured on Nonrecurring Basis [Line Items]
Bank loans, net		$ 30	$ 2
Loans held for sale | Level 2
Fair Value, Assets and Liabilities Measured on Nonrecurring Basis [Line Items]
Bank loans, net		30	2
Loans held for sale | Level 3
Fair Value, Assets and Liabilities Measured on Nonrecurring Basis [Line Items]
Bank loans, net		0	0
Collateral or discounted cash flow | Bank loans - residential
Fair Value, Assets and Liabilities Measured on Nonrecurring Basis [Line Items]
Bank loans, net		10	10
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		8	8
Collateral or discounted cash flow | Bank loans - corporate
Fair Value, Assets and Liabilities Measured on Nonrecurring Basis [Line Items]
Bank loans, net		88	84
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		$ 88	$ 84
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)		0.33	0.22
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)		0.53	0.65
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 3 months 18 days	10 years 4 months 24 days
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)		0.39	0.53