OTHER COMPREHENSIVE INCOME (LOSS) - Summary of other comprehensive income (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2020
Accumulated Other Comprehensive Income (Loss) [Line Items]
Pre-tax	$ (36,504)	$ 31,710	$ (9,344)
Tax	(257)	(5,595)	3,168
Net of tax	(36,761)	26,115	(6,176)
Foreign currency translation adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Pre-tax	(37,920)	6,433	5,601
Tax	0	0	0
Net of tax	(37,920)	6,433	5,601
Pension and other defined benefit plans
Accumulated Other Comprehensive Income (Loss) [Line Items]
Pre-tax	1,907	22,583	(14,955)
Tax	(404)	(4,787)	3,171
Net of tax	1,503	17,796	(11,784)
Cash flow hedges
Accumulated Other Comprehensive Income (Loss) [Line Items]
Pre-tax	(491)	2,694	10
Tax	147	(808)	(3)
Net of tax	$ (344)	$ 1,886	$ 7