Postretirement Benefits - Schedule of Net Benefit (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Apr. 30, 2020	Apr. 30, 2019	Apr. 30, 2020	Apr. 30, 2019
Defined Benefit Plan Disclosure [Line Items]
Defined Contribution Plan, Cost	$ 11
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	2	$ 2	$ 4	$ 4
Interest on obligations	21	30	42	62
Amortization of cumulative loss	24	23	49	47
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement	0	0	0	142
Premiums on pension insurance	3	3	6	4
Expected return on assets	(36)	(35)	(72)	(73)
Net postretirement benefits expense	14	23	29	186
Health and Life Insurance Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	1	1	2	2
Interest on obligations	7	12	14	24
Amortization of cumulative loss	0	0	0	0
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement	0	0	0	0
Premiums on pension insurance	0	0	0	0
Expected return on assets	(5)	(6)	(10)	(11)
Net postretirement benefits expense	$ 3	$ 7	$ 6	$ 15