GOODWILL AND INTANGIBLE ASSETS - Intangible Assets Arising from Business Acquisitions (Details) - USD ($) $ in Thousands	6 Months Ended
	Mar. 31, 2021	Sep. 30, 2020
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 100,461	$ 100,461
Accumulated Amortization	23,031	19,434
Net	$ 77,430	81,027
Developed technology
Finite-Lived Intangible Assets [Line Items]
Weighted Average Estimated Useful Lives	15 years
Gross Carrying Amount	$ 89,096	89,096
Accumulated Amortization	19,205	16,222
Net	$ 69,891	72,874
Intellectual property
Finite-Lived Intangible Assets [Line Items]
Weighted Average Estimated Useful Lives	13 years
Gross Carrying Amount	$ 1,500	1,500
Accumulated Amortization	159	103
Net	$ 1,341	1,397
Trade name
Finite-Lived Intangible Assets [Line Items]
Weighted Average Estimated Useful Lives	20 years
Gross Carrying Amount	$ 5,865	5,865
Accumulated Amortization	1,000	842
Net	$ 4,865	5,023
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Weighted Average Estimated Useful Lives	5 years
Gross Carrying Amount	$ 4,000	4,000
Accumulated Amortization	2,667	2,267
Net	$ 1,333	$ 1,733