OTHER COMPREHENSIVE INCOME (LOSS) (Details) - Summary of Other Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Other Comprehensive Income (Loss), before Tax [Abstract]
Foreign currency translation adjustments	$ 19,714	$ 8,409	$ 18,425		$ (5,070)
Pension and other defined benefit plans	376	836	14,620		1,672
Cash flow hedges	616	(1,428)	746		844
Total other comprehensive income (loss)	20,706	7,817	33,791		(2,554)
Other Comprehensive Income (Loss), Tax [Abstract]
Pension and other defined benefit plans	(129)	(292)	(4,814)		(584)
Cash flow hedges	(176)	408	(218)		(241)
Total other comprehensive income (loss)	(305)	116	(5,032)		(825)
Other Comprehensive Income (Loss), Net of Tax [Abstract]
Foreign currency translation adjustments	19,714	8,409	18,425	$ (5,070)	(5,070)
Pension and other defined benefit plans	247	544	9,806	1,088	1,088
Cash flow hedges	440	(1,020)	528		603
Total other comprehensive income (loss), net of taxes	$ 20,401	$ 7,933	$ 28,759	$ (3,379)	$ (3,379)