POSTRETIREMENT BENEFITS - Asset Allocations by Fair Value Hierarchy (Details) - Pension Plan - USD ($) $ in Thousands	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2020
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 103,925	$ 138,056	$ 106,736
United States equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	29,583	48,274
Non-U.S. equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	22,913	28,787
Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	47,433	59,488
Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	3,996	1,507
Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	79,131	138,056
Level 1 | United States equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	29,583	48,274
Level 1 | Non-U.S. equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	22,913	28,787
Level 1 | Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	22,639	59,488
Level 1 | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	3,996	1,507
Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	24,794	0
Level 2 | United States equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Level 2 | Non-U.S. equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Level 2 | Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	24,794	0
Level 2 | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 0	$ 0