RESTRUCTURING CHARGES - Summary of accrued liability for the restructuring and related charges (Details) - USD ($) $ in Thousands	12 Months Ended
Sep. 30, 2021	Sep. 30, 2020
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance	$ 845	$ 0
Charges	21,418	13,669
Payments	(14,926)	(8,132)
Non-cash charges	(6,655)	(4,692)
Restructuring reserve, ending balance	682	845
Personnel Related Costs
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance	581	0
Charges	3,190	5,620
Payments	(3,353)	(5,039)
Non-cash charges	0	0
Restructuring reserve, ending balance	418	581
Facilities & Exit Costs
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance	264	0
Charges	11,573	3,357
Payments	(11,573)	(3,093)
Non-cash charges		0
Restructuring reserve, ending balance	264	264
Non Cash Facility and Other Costs
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance	0	0
Charges	6,655	4,692
Payments	0	0
Non-cash charges	(6,655)	(4,692)
Restructuring reserve, ending balance	$ 0	$ 0

Amount of cash payments made as the result of exit or disposal activities. Excludes payments associated with a discontinued operation or an asset retirement obligation.

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Balance Type:	credit
Period Type:	duration

- Definition

Discloses the amount charged against the accrued restructuring reserves, or earnings if not previously accrued, during the period for the specified type of restructuring cost.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 420
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (b)(1)
-URI http://asc.fasb.org/extlink&oid=6394359&loc=d3e17939-110869

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 420
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SAB Topic 5.P.4(b)(1))
-URI http://asc.fasb.org/extlink&oid=115931487&loc=d3e140904-122747

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 420
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=6394359&loc=d3e17939-110869

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 420
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SAB Topic 5.P.4(d))
-URI http://asc.fasb.org/extlink&oid=115931487&loc=d3e140904-122747

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Carrying amount (including both current and noncurrent portions of the accrual) as of the balance sheet date pertaining to a specified type of cost associated with exit from or disposal of business activities or restructuring pursuant to a duly authorized plan.

+ References

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

+ Details

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- Definition

Amount of decrease in the reserve for full or partial settlement through consideration other than cash.

+ References

+ Details

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Period Type:	duration

- Details

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- Details

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- Details

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