PENSION & POSTRETIREMENT PLANS - Schedule of Pension and Postretirement Plan Expenses (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Mar. 31, 2024	Mar. 31, 2023
Retirement Benefits [Abstract]
Service cost	$ 9	$ 12	$ 18	$ 24
Interest cost	55	54	110	108
Expected return on plan assets	(74)	(71)	(148)	(142)
Net amortization	(14)	(20)	(28)	(40)
Total	$ (24)	$ (25)	$ (48)	$ (50)