Retirement and Post-Retirement Benefit Plans - Schedule of Funded Status of Defined Benefit and Post-Retirement Benefit Plans (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Oct. 31, 2020	Oct. 31, 2020	Oct. 31, 2019	Oct. 31, 2018
Defined Benefit Plans
Change in fair value of plan assets:
Settlement	$ (2,200)
Change in benefits obligation
Actuarial loss (gain)	214
Post-Retirement Benefit Plans
Change in fair value of plan assets:
Fair value of assets — beginning of year		$ 404	$ 388
Acquisition/ deletion of plan		0	0
Actual return on plan assets		107	44
Employer contributions		4	5
Participant contributions		45	36
Benefits paid		(79)	(69)
Settlement		0	0
Currency impact		0	0
Transfers		0	0
Fair value of assets — end of year	481	481	404	$ 388
Change in benefits obligation
Projected benefit obligation — beginning of year		390	397
Acquisition/ deletion of plan		0	0
Service cost		1	1	1
Interest cost		11	17	15
Participant contributions		45	36
Actuarial loss (gain)		(10)	35
Benefits paid		(79)	(69)
Plan amendments		(8)	(33)
Curtailment		0	0
Settlement		0	0
Special termination benefits		44	6
Transfers		0	0
Currency impact		0	0
Projected benefit obligation — end of year	394	394	390	397
Funded status at end of year	87	87	14
Accumulated benefit obligation
UNITED STATES | Defined Benefit Plans
Change in fair value of plan assets:
Fair value of assets — beginning of year		12,017	10,018
Acquisition/ deletion of plan		0	0
Actual return on plan assets		1,260	2,499
Employer contributions		34	32
Participant contributions		0	0
Benefits paid		(422)	(523)
Settlement		(2,426)	(9)
Currency impact		0	0
Transfers		0	0
Fair value of assets — end of year	10,463	10,463	12,017	10,018
Change in benefits obligation
Projected benefit obligation — beginning of year		13,191	11,167
Acquisition/ deletion of plan		0	0
Service cost		0	0	0
Interest cost		412	491	452
Participant contributions		0	0
Actuarial loss (gain)		589	2,065
Benefits paid		(422)	(523)
Plan amendments		0	0
Curtailment		0	0
Settlement		(2,426)	(9)
Special termination benefits		0	0
Transfers		0	0
Currency impact		0	0
Projected benefit obligation — end of year	11,344	11,344	13,191	11,167
Funded status at end of year	(881)	(881)	(1,174)
Accumulated benefit obligation	11,344	11,344	13,191
Non-U.S. | Defined Benefit Plans
Change in fair value of plan assets:
Fair value of assets — beginning of year		969	850
Acquisition/ deletion of plan		0	(1)
Actual return on plan assets		22	85
Employer contributions		45	44
Participant contributions		18	17
Benefits paid		(33)	(28)
Settlement		(7)	(4)
Currency impact		50	0
Transfers		0	6
Fair value of assets — end of year	1,064	1,064	969	850
Change in benefits obligation
Projected benefit obligation — beginning of year		1,457	1,227
Acquisition/ deletion of plan		3	0
Service cost		64	57	55
Interest cost		17	24	24
Participant contributions		18	17
Actuarial loss (gain)		78	219
Benefits paid		(33)	(28)
Plan amendments		0	4
Curtailment		0	(63)
Settlement		(7)	(4)
Special termination benefits		0	0
Transfers		0	7
Currency impact		67	(3)
Projected benefit obligation — end of year	1,664	1,664	1,457	$ 1,227
Funded status at end of year	(600)	(600)	(488)
Accumulated benefit obligation	$ 1,515	$ 1,515	$ 1,320