POSTRETIREMENT BENEFITS - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2023
Defined Benefit Plan Disclosure [Line Items]
Plan asset allocations (as a percent)	100.00%	100.00%
Employer contributions	$ 280	$ 276
Estimated employer contributions in next fiscal year	350
Defined contribution plans expense	6,570	6,396	$ 5,483
Liability	$ 3,598	$ 3,974
Defined Benefit Plan, Type [Extensible Enumeration]	Pension Plan [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) Excluding Service Cost, Statement of Income or Comprehensive Income [Extensible Enumeration]	Other Comprehensive (Income) Loss, Defined Benefit Plan, after Tax and Reclassification Adjustment, Attributable to Parent	Other Comprehensive (Income) Loss, Defined Benefit Plan, after Tax and Reclassification Adjustment, Attributable to Parent	Other Comprehensive (Income) Loss, Defined Benefit Plan, after Tax and Reclassification Adjustment, Attributable to Parent
Debt securities
Defined Benefit Plan Disclosure [Line Items]
Policy target allocation (as a percentage)	100.00%
Plan asset allocations (as a percent)	97.00%	96.00%
Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Plan asset allocations (as a percent)	3.00%	4.00%