INCOME TAXES - Income Before Income Taxes and Taxes on Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Income Before Income Taxes [Abstract]
Domestic	$ 94,002	$ (45,364)	$ 46,254
Foreign	79,345	108,470	115,457
Total	173,347	63,106	161,711
U.S. federal and state:
Current	20,733	23,461	14,698
Deferred	(7,048)	(23,182)	10,347
Total	13,685	279	25,045
Foreign:
Current	21,053	27,580	26,135
Deferred	(4,219)	(3,968)	488
Total	16,834	23,612	26,623
Total U.S. and foreign	$ 30,519	$ 23,891	$ 51,668