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Benefit Plans Actuarial Assumptions (Details) - USD ($) | 12 Months Ended |
--- | --- | ---
Sep. 30, 2023 | Sep. 30, 2022 | Sep. 30, 2021 | Sep. 30, 2024
Defined Benefit Plan Disclosure |  |  |  |
Defined Benefit Plan, Cost of Living Adjustment Assumption | 0.25% |  |  |
Pension Benefits |  |  |  |
Defined Benefit Plan Disclosure |  |  |  |
Discount rate | 5.60% | 2.90% | 2.75% |
Discount rate | 5.95% | 5.60% | 2.90% |
Rate of compensation increase | 4.05% | 3.32% |  |
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Weighted-Average Interest Crediting Rate | 5.13% | 5.14% |  |
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Weighted-Average Interest Crediting Rate | 5.14% | 5.14% | 5.15% |
Expected return on plan assets | 6.50% | 5.75% | 6.75% |
Defined Benefit Plan, Cost of Living Adjustment Assumption | 2.00% | 2.00% | 2.00% |
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Rate of Compensation Increase |  | 3.32% | 3.37% |
COLA percentage increase (decrease) | 6.00% |  |  |
Actual Return on Plan Assets | 6.13% | (6.64%) | 20.30% |
Other Post-retirement Benefits |  |  |  |
Defined Benefit Plan Disclosure |  |  |  |
Discount rate | 5.65% | 3.05% | 3.05% |
Discount rate | 6.05% | 5.65% | 305.00% |
Defined Benefit Plan, Cost of Living Adjustment Assumption | 2.00% | 2.00% | 2.00% |
Minimum |  |  |  |
Defined Benefit Plan Disclosure |  |  |  |
Rate of compensation increase | 3.00% |  |  |
Maximum |  |  |  |
Defined Benefit Plan Disclosure |  |  |  |
Rate of compensation increase | 5.50% |  |  |
Scenario, Forecast | Pension Benefits |  |  |  |
Defined Benefit Plan Disclosure |  |  |  |
Defined Benefit Plan, Cost of Living Adjustment Assumption Next Fiscal Year |  |  |  | 4.05%
Post-Medicare Eligible [Member] [Member] | Other Post-retirement Benefits |  |  |  |
Defined Benefit Plan Disclosure |  |  |  |
Current health care cost trend rate | 0.00% | 0.00% | 0.00% |
Ultimate health care cost trend rate | 4.00% | 4.00% | 4.00% |
Year health care cost ultimate trend rate is reached for Net Benefit Cost Assumption | 2026 | 2024 | 2024 |
Defined Benefit Plan, Year Health Care Cost Trend Rate Reaches Ultimate Trend Rate | 2026 | 2026 |  |
Pre-Medicare Eligible per Capita Claim Costs | Other Post-retirement Benefits |  |  |  |
Defined Benefit Plan Disclosure |  |  |  |
Current health care cost trend rate | 7.00% | 6.25% | 6.50% |
Ultimate health care cost trend rate | 5.00% | 5.00% | 5.00% |
Defined Benefit Plan, Year Health Care Cost Trend Rate Reaches Ultimate Trend Rate | 2034 | 2031 | 2027 |
Initial health care cost trend rate | $ 0.0750 | $ 0.0700 |  |
Defined Benefit Plan, Year ultimate trend rate is reached for net periodic benefit | 2031 | 2027 |  |
Pre-Medicare Eligible per Capita Contributions | Other Post-retirement Benefits |  |  |  |
Defined Benefit Plan Disclosure |  |  |  |
Current health care cost trend rate | 5.00% | 8.51% | 11.93% |
Ultimate health care cost trend rate | 5.00% | 5.00% | 5.00% |
Defined Benefit Plan, Year ultimate trend rate is reached per capita contributions |  | 2027 |  |
Defined Benefit Plan, Year Health Care Cost Trend Rate Reaches Ultimate Trend Rate | 2022 | 2022 | 2027 |
Initial health care cost trend rate | $ 0.0500 | $ 0.0500 |  |

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- Definition COLA percentage increase (decrease) + References No definition available. + Details
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- Definition The cost of living adjustment percentage used for defined benefit plans. + References No definition available. + Details
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- Definition Weighted average rate for present value of future retirement benefits cash flows, used to determine benefit obligation of defined benefit plan. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (k)(1) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480506/715-20-50-1 + Details
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- Definition Weighted average rate increase of compensation, used to determine benefit obligation of defined benefit plan. Plan includes, but is not limited to, pay-related defined benefit plan. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (k)(2) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480506/715-20-50-1 + Details
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- Definition Weighted-average interest crediting rate used to determine benefit obligation of defined benefit plan. Plan includes, but is not limited to, cash balance and other defined benefit plans with promised interest crediting rate. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (k)(4) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480506/715-20-50-1 + Details
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- Definition Weighted average rate of return on plan assets, reflecting average rate of earnings expected on existing plan assets and expected contributions, used to determine net periodic benefit cost of defined benefit plan. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 8 -Publisher FASB -URI https://asc.fasb.org//1943274/2147480506/715-20-50-8 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (k)(3) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480506/715-20-50-1 + Details
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- Definition Weighted-average interest crediting rate used to determine net periodic benefit cost of defined benefit plan. Plan includes, but is not limited to, cash balance and other defined benefit plans with promised interest crediting rate. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (k)(4) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480506/715-20-50-1 + Details
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- Definition Assumed rate, for next fiscal year, based on annual change in cost of health care cost benefits used to measure expected cost of benefits covered by defined benefit postretirement plan. Factors include, but are not limited to, estimate of health care inflation, change in health care utilization or delivery pattern, technological advances, and change in health status of participant. Excludes factors for change in composition of plan population by age and dependency status. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (l) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480506/715-20-50-1 + Details
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