OTHER COMPREHENSIVE INCOME (LOSS) - Summary of OCI (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total other comprehensive income (loss), pre-tax	$ 6,887	$ (5,308)
Total other comprehensive income (loss), tax	(46)	(142)
Total other comprehensive income (loss), net of taxes	6,841	(5,450)
Foreign currency translation adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total other comprehensive income (loss), pre-tax	6,470	(5,736)
Total other comprehensive income (loss), tax	0	0
Total other comprehensive income (loss), net of taxes	6,470	(5,736)
Pension and other defined benefit plans
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total other comprehensive income (loss), pre-tax	847	271
Total other comprehensive income (loss), tax	(175)	(87)
Total other comprehensive income (loss), net of taxes	672	184
Cash flow hedges
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total other comprehensive income (loss), pre-tax	(430)	157
Total other comprehensive income (loss), tax	129	(55)
Total other comprehensive income (loss), net of taxes	$ (301)	$ 102