GOODWILL AND INTANGIBLE ASSETS - Intangible Assets Arising from Business Acquisitions (Details) - USD ($) $ in Thousands	9 Months Ended
	Jun. 30, 2020	Sep. 30, 2019
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 100,462	$ 98,961
Accumulated Amortization	17,722	12,245
Net	$ 82,740	86,716
Developed technology
Finite-Lived Intangible Assets [Line Items]
Weighted Average Estimated Useful Lives	15 years
Gross Carrying Amount	$ 89,097	89,096
Accumulated Amortization	14,817	10,256
Net	$ 74,280	78,840
Intellectual property
Finite-Lived Intangible Assets [Line Items]
Weighted Average Estimated Useful Lives	13 years
Gross Carrying Amount	$ 1,500	0
Accumulated Amortization	75	0
Net	$ 1,425	0
Trade name
Finite-Lived Intangible Assets [Line Items]
Weighted Average Estimated Useful Lives	20 years
Gross Carrying Amount	$ 5,865	5,865
Accumulated Amortization	763	522
Net	$ 5,102	5,343
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Weighted Average Estimated Useful Lives	5 years
Gross Carrying Amount	$ 4,000	4,000
Accumulated Amortization	2,067	1,467
Net	$ 1,933	$ 2,533