Retirement and Post-Retirement Benefit Plans - Expected Amortization from Accumulated Other Comprehensive Loss During the Next Fiscal Year (Details) $ in Millions	Oct. 31, 2020 USD ($)
Defined Benefit Plans
Defined Benefit Plan, Plan Assets, Allocation [Line Items]
Net actuarial loss (gain)	$ 290
Prior service benefit	(13)
Total expected to be recognized in net periodic benefit cost (credit)	277
Post-Retirement Benefit Plans
Defined Benefit Plan, Plan Assets, Allocation [Line Items]
Net actuarial loss (gain)	(2)
Prior service benefit	0
Total expected to be recognized in net periodic benefit cost (credit)	$ (2)