Pension and Other Postretirement Benefits - Additional Information (Details) - USD ($) $ in Millions |
9 Months Ended | |
|---|---|---|
Jul. 31, 2016 |
Sep. 30, 2016 |
|
| Other Postretirement Benefit Cost | ||
| Defined Benefit Plan Disclosure [Line Items] | ||
| Reduction in future benefits payable | $ 156 | |
| Increase in fair value of plan assets | 60 | |
| Increase in actuarial losses | 127 | |
| Reduction to net accrued postretirement benefit obligation | $ 89 | |
| Plan amendment amortization period | 10 years 7 days | |
| Company contributions | $ 17 | |
| Pension Plan Asset | ||
| Defined Benefit Plan Disclosure [Line Items] | ||
| Company contributions | 25 | |
| Expected contributions during the remainder of 2016 | $ 8 |