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Benefit Plans Contributions (Details) - USD ($) $ in Millions | 3 Months Ended | 9 Months Ended |  |
--- | --- | --- | --- | ---
Jun. 30, 2020 | Jun. 30, 2020 | Mar. 31, 2020 | Sep. 30, 2019
Retirement Plan Disclosure |  |  |  |
Assets for Plan Benefits, Defined Benefit Plan | $ 7,800 | $ 7,800 | $ 6,800 | $ 8,000
Remaining Employer Contributions |  | 75 |  |
Other Pension Plan |  |  |  |
Retirement Plan Disclosure |  |  |  |
Defined benefit plan contributions |  | 225 |  |
defined benefit plan, plan assets, monthly contributions by employer |  | 25 |  |
Other Post-retirement Benefits |  |  |  |
Retirement Plan Disclosure |  |  |  |
Defined benefit plan contributions |  | 19 |  |
SERP |  |  |  |
Retirement Plan Disclosure |  |  |  |
Defined benefit plan contributions | 5 |  |  |
Rebates [Member] |  |  |  |
Retirement Plan Disclosure |  |  |  |
Defined benefit plan contributions |  | 4 |  |
401K [Member] |  |  |  |
Retirement Plan Disclosure |  |  |  |
Defined benefit plan contributions |  | $ 67 |  |
Minimum | Other Pension Plan |  |  |  |
Retirement Plan Disclosure |  |  |  |
Defined benefit plan contributions | $ 300 |  |  |

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