GOODWILL AND OTHER INTANGIBLE ASSETS - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
Goodwill and Intangible Assets Disclosure [Abstract]
Amortization expense on intangible assets	$ 31,562	$ 23,313	$ 20,821
Future amortization expense [Abstract]
Future amortization expense 2019	32,128
Future amortization expense 2020	30,388
Future amortization expense 2021	28,976
Future amortization expense 2022	27,387
Future amortization expense 2023	$ 25,815