OTHER COMPREHENSIVE INCOME (LOSS) (Details) - Summary of Other Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
Other Comprehensive Income (Loss), Net of Tax [Abstract]
Foreign currency translation adjustments, Pre-tax	$ 17,284	$ (56,358)	$ (23,933)
Pension and other defined benefit plans, Pre-tax	(8,694)	(6,655)	(6,061)
Cash flow hedge, Pre-tax	(2,593)	662	386
Available-for-sale securities, Pre-tax		(1,370)	1,370
Total other comprehensive income (loss), Pre-tax	5,997	(63,721)	(28,238)
Foreign currency translation adjustments, Tax	0	0	0
Pension and other defined benefit plans, Tax	3,043	2,329	2,147
Cash flow hedge, Tax	907	(232)	(134)
Available-for-sale securities, Tax		500	(500)
Total other comprehensive income (loss), Tax	3,950	2,597	1,513
Foreign currency translation adjustments, Net of Tax	17,284	(56,358)	(23,933)
Pension and other defined benefit plans, Net of Tax	(5,651)	(4,326)	(3,914)
Cash flow hedge, Net of Tax	(1,686)	430	252
Available-for-sale securities, Net of Tax	0	(870)	870
Total other comprehensive income (loss), net of taxes	$ 9,947	$ (61,124)	$ (26,725)