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Benefit Plans Contributions (Details) - USD ($) $ in Millions | 3 Months Ended | 6 Months Ended |
--- | --- | --- | ---
Mar. 31, 2020 | Mar. 31, 2020 | Sep. 30, 2019
Retirement Plan Disclosure |  |  |
Assets for Plan Benefits, Defined Benefit Plan | $ 6,800 | $ 6,800 | $ 8,000
Remaining Employer Contributions |  | 150 |
Contributions to 401K |  | 46 |
Other Pension Plan |  |  |
Retirement Plan Disclosure |  |  |
Defined benefit plan contributions |  | 150 |
defined benefit plan, plan assets, monthly contributions by employer |  | 25 |
Other Post-retirement Benefits |  |  |
Retirement Plan Disclosure |  |  |
Defined benefit plan contributions |  | $ 16 |
SERP |  |  |
Retirement Plan Disclosure |  |  |
Defined benefit plan contributions | 5 |  |
Minimum | Other Pension Plan |  |  |
Retirement Plan Disclosure |  |  |
Defined benefit plan contributions | $ 300 |  |

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- Definition Amount of asset, recognized in statement of financial position, for overfunded defined benefit pension and other postretirement plans. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 45 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=109237824&loc=d3e1731-114919 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=109237824&loc=d3e1703-114919 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(17)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(a)(10)) -URI http://asc.fasb.org/extlink&oid=119400593&loc=d3e572229-122910 Reference 6: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(10)) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 + Details
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