LONG-TERM DEBT - Summary of Long-Term Debt (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Sep. 30, 2021	Jun. 22, 2020
Debt Instrument [Line Items]
Long-term debt, Outstanding Balance	$ 1,997,555	$ 1,060,506
less: Current portion, Outstanding Balance	(25,110)	(12,486)
Long-term debt, Outstanding Balance, Non-current	1,972,445	1,048,020
Original Issuer Premium/(Discount)	(1,680)	315
Capitalized Fees & Expenses	(29,040)	(15,138)
Long-term debt, Balance Sheet	1,966,835	1,045,683
less: Current portion, Balance Sheet	(25,110)	(12,486)
Long-term debt, Balance Sheet, Non-current	1,941,725	1,033,197
Senior notes due 2028
Debt Instrument [Line Items]
Long-term debt, Outstanding Balance	1,000,000	1,000,000
Original Issuer Premium/(Discount)	290	315
Capitalized Fees & Expenses	(12,257)	(13,293)
Long-term debt, Balance Sheet	$ 988,033	$ 987,022
Coupon Interest Rate	5.75%	5.75%	5.75%
Term Loan B 2029
Debt Instrument [Line Items]
Long-term debt, Outstanding Balance	$ 800,000	$ 0
Original Issuer Premium/(Discount)	(1,970)	0
Capitalized Fees & Expenses	(15,235)	0
Long-term debt, Balance Sheet	782,795	0
Revolver due 2025
Debt Instrument [Line Items]
Long-term debt, Outstanding Balance	153,146	13,483
Original Issuer Premium/(Discount)	0	0
Capitalized Fees & Expenses	(1,473)	(1,718)
Long-term debt, Balance Sheet	151,673	11,765
Finance lease - real estate
Debt Instrument [Line Items]
Long-term debt, Outstanding Balance	13,757	14,594
Original Issuer Premium/(Discount)	0	0
Capitalized Fees & Expenses	0	(4)
Long-term debt, Balance Sheet	13,757	14,590
Non US lines of credit
Debt Instrument [Line Items]
Long-term debt, Outstanding Balance	11,713	3,012
Original Issuer Premium/(Discount)	0	0
Capitalized Fees & Expenses	(9)	(17)
Long-term debt, Balance Sheet	11,704	2,995
Non US term loans
Debt Instrument [Line Items]
Long-term debt, Outstanding Balance	15,948	25,684
Original Issuer Premium/(Discount)	0	0
Capitalized Fees & Expenses	(52)	(91)
Long-term debt, Balance Sheet	15,896	25,593
Other long term debt
Debt Instrument [Line Items]
Long-term debt, Outstanding Balance	2,991	3,733
Original Issuer Premium/(Discount)	0	0
Capitalized Fees & Expenses	(14)	(15)
Long-term debt, Balance Sheet	$ 2,977	$ 3,718

Amount of long term capitalized fees and expenses.

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The current portion of long term debt gross value.

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The carrying amount of long-term debt, excluding amounts to be repaid within one year or the normal operating cycle, if longer (current maturities).

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Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

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Contractual interest rate for funds borrowed, under the debt agreement.

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Amount, after accumulated amortization, of debt discount (premium).

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Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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