OTHER COMPREHENSIVE INCOME (LOSS) (Details) - Summary of Other Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
Other Comprehensive Income (Loss), Net of Tax [Abstract]
Foreign currency translation adjustments, Pre-tax	$ 9,403	$ 10,667	$ 17,284
Pension and other defined benefit plans, Pre-tax	24,081	14,160	(8,694)
Cash flow hedge, Pre-tax	900	1,370	(2,593)
Total other comprehensive income (loss), Pre-tax	34,384	26,197	5,997
Foreign currency translation adjustments, Tax	0	0	0
Pension and other defined benefit plans, Tax	(7,700)	(4,957)	3,043
Cash flow hedge, Tax	(315)	(480)	907
Total other comprehensive income (loss), Tax	(8,015)	(5,437)	3,950
Foreign currency translation adjustments, Net of Tax	9,403	10,667	17,284
Pension and other defined benefit plans, Net of Tax	16,381	9,203	(5,651)
Cash flow hedge, Net of Tax	585	890	(1,686)
Total other comprehensive income, net of taxes	$ 26,369	$ 20,760	$ 9,947

Amount before tax, after reclassification adjustments of other comprehensive income (loss).

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