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LEASES - Narrative (Details) $ in Millions | 12 Months Ended |
--- | --- | ---
Sep. 30, 2020 USD ($) renewal_option | Sep. 30, 2019 USD ($) | Sep. 30, 2018 USD ($) | Oct. 01, 2019
Lessee, Lease, Description [Line Items] |  |  |  |
Weighted average incremental borrowing rate applied to operating lease liabilities | 2.70% |  |  | 2.90%
Operating lease expense | $ | $ 18.6 | $ 15.5 | $ 13.7 |
Tulsa Corporate Office Lease |  |  |  |
Lessee, Lease, Description [Line Items] |  |  |  |
Number of renewal options | 2 |  |  |
Renewal option term | 5 years |  |  |
Tulsa Industrial Facility Lease |  |  |  |
Lessee, Lease, Description [Line Items] |  |  |  |
Number of renewal options | 2 |  |  |
Renewal option term | 2 years |  |  |

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- Definition Lessee Operating Lease, Number Of Options To Extend + References No definition available. + Details
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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. + References No definition available. + Details
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- Definition Term of lessee's operating lease renewal, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 20 -Section 50 -Paragraph 3 -Subparagraph (a)(3) -URI http://asc.fasb.org/extlink&oid=121609121&loc=SL77918673-209980 + Details
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- Definition Amount of operating lease expense. Excludes sublease income. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 20 -Section 45 -Paragraph 4 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=121603541&loc=SL77918638-209977 + Details
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- Definition Weighted average discount rate for operating lease calculated at point in time. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 20 -Section 50 -Paragraph 4 -Subparagraph (g)(4) -URI http://asc.fasb.org/extlink&oid=121609121&loc=SL77918686-209980 Reference 2: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 20 -Section 55 -Paragraph 53 -URI http://asc.fasb.org/extlink&oid=121568110&loc=SL77918982-209971 + Details
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- Details
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- Details
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