Postretirement Benefits - Schedule of Net Benefit (Details) - USD ($) $ in Millions	3 Months Ended
	Jan. 31, 2019	Jan. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Defined Contribution Plan, Cost	$ 8	$ 7
Employer contributions	131	21
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	2	2
Interest on obligations	32	27
Amortization of cumulative loss	24	26
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement	142	9
Premiums on pension insurance	1	2
Expected return on assets	(38)	(40)
Net postretirement benefits expense	163	26
Health and Life Insurance Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	1	1
Interest on obligations	12	11
Amortization of cumulative loss	0	2
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement	0	0
Premiums on pension insurance	0	0
Expected return on assets	(5)	(6)
Net postretirement benefits expense	$ 8	$ 8