Retirement and Post-Retirement Employee Benefit Plans - Asset Allocation Postretirement Benefit Plan (Details) - Postretirement Plans |
Sep. 30, 2019 |
Sep. 30, 2018 |
---|---|---|
Diversified investment funds | ||
Defined Benefit Plan Disclosure [Line Items] | ||
Asset Allocation | 97.10% | 97.50% |
Cash and cash equivalents | ||
Defined Benefit Plan Disclosure [Line Items] | ||
Asset Allocation | 2.90% | 2.50% |