EMPLOYEE BENEFIT PLANS - PENSION AND OTHER POSTEMPLOYMENT BENEFIT PLANS, NARRATIVE (Details)	12 Months Ended
	Sep. 30, 2025 USD ($) plan	Sep. 30, 2024 USD ($)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Number of noncontributory defined benefit retirement plans (in plans) | plan	2
Required number of years of service (more than)	1 year
Years of service and average compensation, basis period for plan benefits	60 months
Amortization period for plan amendment	8 years
Pension
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Employer discretionary contributions	$ 0	$ 0
Employer contributions	539,000	535,000
OPEB
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Employer contributions	486,000	$ 7,846,000
OPEB | Maximum
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Estimated future employer contributions over the next five years	$ 3,000,000.0