| LONG-TERM DEBT - Loss Recognized on Derivatives (Details) - Cash Flow Hedging - Interest Rate Swaps - USD ($) $ in Thousands | 12 Months Ended | ||
|---|---|---|---|
| Sep. 30, 2018 | Sep. 30, 2017 | Sep. 30, 2016 | |
| Interest Expense | |||
| Debt Instrument [Line Items] | |||
| Amount of Gain (Loss) Recognized in Income on Derivatives | $ 1,380 | $ 1,752 | $ (3,146) | 
| Amount of Gain (Loss) Reclassified from AOCI into Income(Effective Portion) | 1,042 | 1,069 | (1,919) | 
| Other Comprehensive Income (Loss) | |||
| Debt Instrument [Line Items] | |||
| Amount of Gain (Loss) Recognized in AOCI on Derivatives | $ 6,095 | $ 7,043 | $ (3,230) | 
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. No definition available. 
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- Definition Amount of increase (decrease) in the fair value of derivatives recognized in the income statement. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- Definition The effective portion of net gain (loss) reclassified from accumulated other comprehensive income into income on derivative instruments designated and qualifying as hedging instruments. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- Definition The effective portion of gains and losses (net) on derivative instruments designated and qualifying as hedging instruments that was recognized in other comprehensive income during the current period. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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