GOODWILL AND INTANGIBLE ASSETS - Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	12 Months Ended
	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Impairment Effects on Earnings Per Share [Line Items]
Amortization		$ 5,800	$ 5,400	$ 1,100
Expected amortization in the next fiscal year		7,000
Expected amortization in 2020	$ 7,000		7,000
Expected amortization in 2021	7,000		7,000
Expected amortization in 2022	7,000		7,000
Expected amortization in 2023		6,400
Expected amortization in 2024		6,200
Goodwill	64,777	$ 82,786	64,777	$ 51,705
Goodwill impairment loss			4,719
TerraVici
Impairment Effects on Earnings Per Share [Line Items]
Goodwill	4,700		$ 4,700
Goodwill impairment loss	4,700
Goodwill impairment loss, net of tax	$ 3,500
Goodwill impairment loss per diluted share (in dollars per share)	$ 0.03
Intangible assets impairment loss	$ 900
Intangible assets impairment loss, net of tax	$ 700
Intangible assets impairment loss per diluted share (in dollars per share)	$ 0.01