GOODWILL AND OTHER INTANGIBLES - Narrative (Details)	3 Months Ended		6 Months Ended
	Mar. 31, 2021 USD ($)	Mar. 31, 2020 USD ($)	Mar. 31, 2021 USD ($)	Mar. 31, 2020 USD ($) unit
Goodwill and Intangible Assets Disclosure [Abstract]
Carry amount of intangible assets related to foreign currency translation	$ 5,250,000
Amortization expense	2,433,000	$ 2,403,000	$ 4,811,000	$ 4,796,000
Estimated amortization expense, remainder of fiscal year	4,574,000		4,574,000
Estimated amortization expense, year one	9,376,000		9,376,000
Estimated amortization expense, year two	9,224,000		9,224,000
Estimated amortization expense, year three	9,198,000		9,198,000
Estimated amortization expense, year four	9,198,000		9,198,000
Estimated amortization expense, year five	9,198,000		9,198,000
Estimated amortization expense, thereafter	$ 78,080,000		78,080,000
Number of reporting units for goodwill impairment testing | unit				3
Goodwill impairment			0
Indefinite-lived intangible asset (excluding goodwill) impairment			$ 0