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Benefit Plans Asset Holdings (Details) - USD ($) | 12 Months Ended
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Sep. 30, 2019 | Sep. 30, 2018 | Sep. 30, 2017
Defined Benefit Plan Disclosure |  |  |
Target Allocation | 100.00% |  |
Plan Asset Allocations | 100.00% | 100.00% |
Global public equity |  |  |
Defined Benefit Plan Disclosure |  |  |
Target Allocation | 35.00% |  |
Plan Asset Allocations | 37.00% | 44.00% |
Public real assets |  |  |
Defined Benefit Plan Disclosure |  |  |
Target Allocation | 15.00% |  |
Plan Asset Allocations | 15.00% | 15.00% |
Private equity |  |  |
Defined Benefit Plan Disclosure |  |  |
Target Allocation | 8.00% |  |
Plan Asset Allocations | 10.00% | 7.00% |
Safety oriented fixed income |  |  |
Defined Benefit Plan Disclosure |  |  |
Target Allocation | 17.00% |  |
Plan Asset Allocations | 18.00% | 16.00% |
Opportunistic fixed income |  |  |
Defined Benefit Plan Disclosure |  |  |
Target Allocation | 15.00% |  |
Plan Asset Allocations | 12.00% | 10.00% |
Private real assets |  |  |
Defined Benefit Plan Disclosure |  |  |
Target Allocation | 10.00% |  |
Plan Asset Allocations | 8.00% | 8.00% |
Other Post-retirement Benefits |  |  |
Defined Benefit Plan Disclosure |  |  |
Actuarial assumption COLA | $ 0.0221 | $ 1.8400 | $ 0.9900

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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=118257860&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=118255775&loc=d3e1928-114920 + Details
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