Postretirement Benefits - Narrative (Details) - USD ($)	3 Months Ended		6 Months Ended
	Apr. 30, 2021	Apr. 30, 2020	Apr. 30, 2021	Apr. 30, 2020	Mar. 11, 2021
Defined Benefit Plan Disclosure [Line Items]
Defined contribution expense	$ 9,000,000	$ 11,000,000	$ 16,000,000	$ 19,000,000
Profit sharing accrual			31,000,000	0
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Employer contributions			191,000,000	30,000,000
Employer contributions, current period, CARES Act	157,000,000		157,000,000
Expected future contributions remainder of fiscal year	2,000,000		2,000,000		$ 129,000,000
Pension recognized			9,000,000
Contractual termination benefits	0	0	9,000,000	0
Curtailment gain (loss)			2,000,000
Other Postretirement Benefits Plan
Defined Benefit Plan Disclosure [Line Items]
Contractual termination benefits	$ 0	$ 0	3,000,000	$ 0
Curtailment gain (loss)			(7,000,000)
Net actuarial gain (loss)			$ 43,000,000