EMPLOYEE BENEFIT PLANS - ASSUMED HCCTR (Details) - OPEB	12 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2023
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
HCCTR	9.40%	8.80%	7.40%
Ultimate HCCTR	4.50%	4.50%	4.50%