INCOME TAXES, Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2023
Income Tax Disclosure [Line Items]
Investment tax credits	$ 10	$ 20	$ 11
Unamortized equity investments accounted for under the proportional amortization method	$ 23
Unamortized equity investments accounted for under the proportional amortization method, location	Other assets
Deferred tax assets, net of valuation allowance	$ 973	971
Cumulative undistributed earnings attributable to foreign subsidiaries	669
Current tax receivable	79	28
Current tax payable	5	0
Income tax penalties and interest accrued	9	14
Unrecognized tax benefits that would impact effective tax rate	41	$ 41	35
Decrease in unrecognized tax benefits is reasonably possible	11
LIHTC investments
Income Tax Disclosure [Line Items]
Amortization of investments accounted for under the proportional amortization method, statements of income location		Provision for income taxes
Amortization of investments accounted for under the proportional amortization method	3	$ 3	3
Tax credits related to investments accounted for under the proportional amortization method	$ 3	$ 3	$ 3
Renewable energy tax credit investments
Income Tax Disclosure [Line Items]
Amortization of investments accounted for under the proportional amortization method, statements of income location	Provision for income taxes	Provision for income taxes	Provision for income taxes
Amortization of investments accounted for under the proportional amortization method	$ 43	$ 28	$ 86
Tax credits related to investments accounted for under the proportional amortization method	44	28	81
Other tax benefits related to investments accounted for under the proportional amortization method	0	0	$ 9
Remaining commitments related to investments accounted for under the proportional amortization method	47
Other payables
Income Tax Disclosure [Line Items]
Net deferred tax liabilities	$ 0	$ 4