PENSION AND POSTRETIREMENT PLANS - Schedule of Retirement Plans Expense (Details) - Pension Plan - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2023
U.S. Plans
Defined Benefit Plan Disclosure [Line Items]
Service cost (benefits earned during the period)	$ 50	$ 17	$ 25
Interest cost	140	169	164
Expected return on plan assets	(252)	(259)	(247)
Net amortization and other	22	(43)	(55)
Net periodic pension expense (income)	(40)	(116)	(113)
Defined contribution plans	140	130	111
Total retirement plans expense (income)	100	14	(2)
Non-U.S. Plans
Defined Benefit Plan Disclosure [Line Items]
Service cost (benefits earned during the period)	22	20	20
Interest cost	46	49	50
Expected return on plan assets	(43)	(38)	(39)
Net amortization and other	3	6	18
Net periodic pension expense (income)	28	37	49
Defined contribution plans	67	70	49
Total retirement plans expense (income)	$ 95	$ 107	$ 98