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Benefit Plans Asset Holdings (Details) - USD ($) | 12 Months Ended
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Sep. 30, 2023 | Sep. 30, 2022 | Sep. 30, 2021
Defined Benefit Plan Disclosure |  |  |
Target Allocation | 100.00% |  |
Plan Asset Allocations | 100.00% | 100.00% |
Growth Assets |  |  |
Defined Benefit Plan Disclosure |  |  |
Target Allocation | 17.00% |  |
Plan Asset Allocations | 22.00% | 20.00% |
Defensive growth assets |  |  |
Defined Benefit Plan Disclosure |  |  |
Target Allocation | 30.00% |  |
Plan Asset Allocations | 33.00% | 34.00% |
Defensive Assets |  |  |
Defined Benefit Plan Disclosure |  |  |
Target Allocation | 33.00% |  |
Plan Asset Allocations | 17.00% | 18.00% |
Inflation-sensitive Assets |  |  |
Defined Benefit Plan Disclosure |  |  |
Target Allocation | 20.00% |  |
Plan Asset Allocations | 28.00% | 28.00% |
Other Post-retirement Benefits |  |  |
Defined Benefit Plan Disclosure |  |  |
Actuarial assumption COLA | $ 0.06 | $ 0.035 | $ 0.0113

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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 -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 55 -Paragraph 17 -Publisher FASB -URI https://asc.fasb.org//1943274/2147480482/715-20-55-17 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (d)(i) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480506/715-20-50-1 + Details
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