ACCUMULATED OTHER COMPREHENSIVE INCOME - Components of AOCI (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income	$ 525,668	$ 487,352
Fair value of derivatives, tax	1,015	2,762
Pension liability, tax	(1,620)	(1,786)
Cumulative foreign currency translation
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income	(190,196)	(203,310)
Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income	9,032	7,937
Minimum pension liabilities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income	6,760	5,182
Accumulated Other Comprehensive (Loss) Income (net of tax)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income	$ (174,404)	$ (190,191)