GOODWILL AND INTANGIBLE ASSETS - Intangible assets (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Sep. 30, 2018
Intangible Assets
Gross Carrying Amount, Finite-lived	$ 79,900	$ 79,700
Accumulated Amortization	9,369	6,493
Net, Finite-lived	70,531	73,207
Developed technology
Intangible Assets
Gross Carrying Amount, Finite-lived	70,200	70,000
Accumulated Amortization	7,922	5,589
Net, Finite-lived	62,278	64,411
Trade name
Intangible Assets
Gross Carrying Amount, Finite-lived	5,700	5,700
Accumulated Amortization	380	237
Net, Finite-lived	5,320	5,463
Customer relationships
Intangible Assets
Gross Carrying Amount, Finite-lived	4,000	4,000
Accumulated Amortization	1,067	667
Net, Finite-lived	$ 2,933	$ 3,333