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EMPLOYEE BENEFIT PLANS - Actual and weighted-average assets allocation for qualified benefit plans (Details) | Sep. 30, 2021 | Sep. 30, 2020
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Defined Benefit Plan Disclosure [Line Items] |  |
Defined benefit plan, total actual weighted average plan asset allocations | 100.00% | 100.00%
Target plan asset allocations | 100.00% |
Cash and equivalents |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Defined benefit plan, total actual weighted average plan asset allocations | 1.20% | 0.40%
Target plan asset allocations | 0.00% |
Equity securities |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Defined benefit plan, total actual weighted average plan asset allocations | 52.50% | 48.50%
Target plan asset allocations | 63.00% |
Fixed Income Funds |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Defined benefit plan, total actual weighted average plan asset allocations | 26.90% | 31.90%
Target plan asset allocations | 37.00% |
Other Asset Categories |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Defined benefit plan, total actual weighted average plan asset allocations | 19.40% | 19.20%
Target plan asset allocations | 0.00% |

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- Definition Percentage of target investment allocation to total plan assets. Includes, but is not limited to, percentage on weighted-average basis if more than one plan. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 55 -Paragraph 17 -URI http://asc.fasb.org/extlink&oid=123450688&loc=d3e4179-114921 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (d)(i) -URI http://asc.fasb.org/extlink&oid=123447040&loc=d3e1928-114920 + Details
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- Definition Percentage of actual investment allocation to total plan assets. Includes, but is not limited to, percentage on weighted-average basis if more than one plan. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (d)(i) -URI http://asc.fasb.org/extlink&oid=123447040&loc=d3e1928-114920 + Details
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