OTHER COMPREHENSIVE INCOME (LOSS) - AOCI (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Sep. 30, 2021	Dec. 31, 2020	Sep. 30, 2020
Class of Stock [Line Items]
Accumulated other comprehensive income (loss)	$ 812,385	$ 807,158	$ 740,047	$ 700,151
Foreign currency translation adjustments
Class of Stock [Line Items]
Accumulated other comprehensive income (loss)	(21,569)	(19,250)
Pension and other defined benefit plans
Class of Stock [Line Items]
Accumulated other comprehensive income (loss)	(28,134)	(28,802)
Cash flow hedges
Class of Stock [Line Items]
Accumulated other comprehensive income (loss)	975	2,075
Accumulated other comprehensive income (loss), attributable to parent
Class of Stock [Line Items]
Accumulated other comprehensive income (loss)	$ (48,728)	$ (45,977)	$ (58,951)	$ (72,092)