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LONG-TERM DEBT - Summary of interest expense incurred (Details) - USD ($) $ in Thousands | 12 Months Ended
--- | ---
Sep. 30, 2025 | Sep. 30, 2024 | Sep. 30, 2023
Debt Instrument [Line Items] |  |  |
Cash Interest | $ 91,836 | $ 99,884 | $ 97,213
Capitalized interest | (765) | (1,006) | (142)
Amort. Debt (Premium) Discount | 89 | 116 | 124
Amort. Deferred Cost & Other Fees | 4,087 | 4,086 | 4,108
Total Interest Expense | $ 96,012 | $ 104,086 | $ 101,445
Senior Notes due 2028 |  |  |
Debt Instrument [Line Items] |  |  |
Effective Interest Rate | 5.95% | 5.93% | 5.95%
Cash Interest | $ 56,058 | $ 56,050 | $ 56,050
Amort. Debt (Premium) Discount | (48) | (48) | (48)
Amort. Deferred Cost & Other Fees | 2,020 | 2,020 | 2,020
Total Interest Expense | $ 58,030 | $ 58,022 | $ 58,022
Term Loan B due 2029 |  |  |
Debt Instrument [Line Items] |  |  |
Effective Interest Rate | 6.94% | 8.17% | 7.49%
Cash Interest | $ 30,131 | $ 36,193 | $ 35,321
Amort. Debt (Premium) Discount | 137 | 163 | 172
Amort. Deferred Cost & Other Fees | 1,251 | 1,304 | 1,398
Total Interest Expense | 31,519 | 37,660 | 36,891
Revolver due 2028 |  |  |
Debt Instrument [Line Items] |  |  |
Cash Interest | 5,945 | 8,018 | 4,282
Amort. Debt (Premium) Discount | 0 | 0 | 0
Amort. Deferred Cost & Other Fees | 746 | 746 | 646
Total Interest Expense | 6,691 | 8,764 | $ 4,928
Finance lease - real estate |  |  |
Debt Instrument [Line Items] |  |  |
Effective Interest Rate |  |  | 5.60%
Cash Interest |  |  | $ 680
Amort. Debt (Premium) Discount |  |  | 0
Amort. Deferred Cost & Other Fees |  |  | 0
Total Interest Expense |  |  | 680
Non U.S. lines of credit |  |  |
Debt Instrument [Line Items] |  |  |
Cash Interest | 17 | 43 | 630
Amort. Debt (Premium) Discount | 0 | 0 | 0
Amort. Deferred Cost & Other Fees | 70 | 15 | 42
Total Interest Expense | 87 | 58 | 672
Other debt |  |  |
Debt Instrument [Line Items] |  |  |
Cash Interest | 450 | 586 | 392
Amort. Debt (Premium) Discount | 0 | 1 | 0
Amort. Deferred Cost & Other Fees | 0 | 1 | 2
Total Interest Expense | $ 450 | $ 588 | $ 394

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- Definition Amount of noncash expense included in interest expense to amortize debt discount and premium associated with the related debt instruments. Excludes amortization of financing costs. Alternate captions include noncash interest expense. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Section 45 -Paragraph 28 -Subparagraph (b) -SubTopic 10 -Topic 230 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482740/230-10-45-28 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 220 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03(8)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147483621/220-10-S99-2 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 470 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1F -Subparagraph (b)(2) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481139/470-20-50-1F Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 835 -SubTopic 30 -Name Accounting Standards Codification -Section 45 -Paragraph 3 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482925/835-30-45-3 + Details
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