OTHER COMPREHENSIVE INCOME (LOSS) - Summary of OCI (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total other comprehensive income (loss), pre-tax	$ 13,290	$ 6,887
Total other comprehensive income (loss), tax	(149)	(46)
Total other comprehensive income (loss), net of taxes	13,141	6,841
Foreign currency translation adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total other comprehensive income (loss), pre-tax	12,123	6,470
Total other comprehensive income (loss), tax	0	0
Total other comprehensive income (loss), net of taxes	12,123	6,470
Pension and other defined benefit plans
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total other comprehensive income (loss), pre-tax	2,150	847
Total other comprehensive income (loss), tax	(444)	(175)
Total other comprehensive income (loss), net of taxes	1,706	672
Cash flow hedges
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total other comprehensive income (loss), pre-tax	(983)	(430)
Total other comprehensive income (loss), tax	295	129
Total other comprehensive income (loss), net of taxes	$ (688)	$ (301)