EMPLOYEE BENEFIT PLANS - Schedule of Pension and post-retirement plan assets by asset category (Details) - USD ($) $ in Thousands	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2023
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	$ 132,376	$ 158,705
Defined benefit plan, fair value of plan assets, subtotal excluding accrued income and plan receivables	131,368	158,182
Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets, subtotal excluding accrued income and plan receivables	97,941	111,907
Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets, subtotal excluding accrued income and plan receivables	26,842	36,296
Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	6,585	9,979	$ 10,459
Defined benefit plan, fair value of plan assets, subtotal excluding accrued income and plan receivables	6,585	9,979
Cash and equivalents
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	3,167	4,522
Cash and equivalents \| Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	3,167	4,522
Cash and equivalents \| Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	0	0
Cash and equivalents \| Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	0	0
Government agency securities
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	18,245	11,006
Government agency securities \| Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	10,091	5,890
Government agency securities \| Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	8,154	5,116
Government agency securities \| Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	0	0
Debt instruments
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	84,628	48,849
Debt instruments \| Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	75,344	42,705
Debt instruments \| Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	9,284	6,144
Debt instruments \| Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	0	0
Equity securities
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	7,134	41,786
Equity securities \| Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	7,134	41,786
Equity securities \| Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	0	0
Equity securities \| Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	0	0
Commingled funds
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	6,585	14,838
Commingled funds \| Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	0	0
Commingled funds \| Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	0	4,859
Commingled funds \| Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	6,585	9,979
Limited partnerships and hedge fund investments
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	9,404	20,177
Limited partnerships and hedge fund investments \| Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	0	0
Limited partnerships and hedge fund investments \| Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	9,404	20,177
Limited partnerships and hedge fund investments \| Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	0	0
Other securities
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	2,205	17,004
Other securities \| Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	2,205	17,004
Other securities \| Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	0	0
Other securities \| Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	0	0
Accrued income and plan receivables
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	$ 1,008	$ 523