GOODWILL AND INTANGIBLE ASSETS - Intangible Assets Arising from Business Acquisitions (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 98,961	$ 79,700
Accumulated Amortization	12,245	6,493
Net	$ 86,716	73,207
Developed technology
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted Average Estimated Useful Lives	15 years
Gross Carrying Amount	$ 89,096	70,000
Accumulated Amortization	10,256	5,589
Net	$ 78,840	64,411
Trade name
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted Average Estimated Useful Lives	20 years
Gross Carrying Amount	$ 5,865	5,700
Accumulated Amortization	522	237
Net	$ 5,343	5,463
Customer relationships
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted Average Estimated Useful Lives	5 years
Gross Carrying Amount	$ 4,000	4,000
Accumulated Amortization	1,467	667
Net	$ 2,533	$ 3,333