FAIR VALUE, Investments in Private Equity Measured at Net Asset Value Per Share (Details) - Recurring - USD ($) $ in Millions	Sep. 30, 2023	Sep. 30, 2022
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Private equity investments measured at NAV, recorded value	$ 101	$ 90
Private equity investments not measured at NAV, recorded value	7	5
Total private equity investments	108	95
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Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Private equity investments measured at NAV, unfunded commitment	$ 29	$ 39