Postretirement Benefits - Summary of Changes in the Defined Benefit Plans (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Oct. 31, 2013	Oct. 31, 2015	Oct. 31, 2014	Oct. 31, 2013
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Curtailments	$ (4)
Pension Benefits
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligations at beginning of year		$ 4,041	$ 3,943
Service cost		13	12	$ 20
Interest on obligations		142	158	143
Actuarial loss (gain)		146	176
Curtailments		0	(2)
Contractual termination benefits		(1)	23
Currency translation		(53)	49
Defined Benefit Plan, Contributions by Plan Participants		0	0
Subsidy receipts		0	0
Benefits paid		(309)	(318)
Benefit obligations at end of year	3,943	3,979	4,041	3,943
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at beginning of year		2,627	2,519
Actual return on plan assets		27	206
Currency translation		(51)	42
Employer contributions		113	164
Benefits paid		(294)	(304)
Fair value of plan assets at end of year	2,519	2,422	2,627	2,519
Funded status at year end		(1,557)	(1,414)
Health and Life Insurance Benefits
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligations at beginning of year		1,957	1,674
Service cost		6	5	7
Interest on obligations		71	68	62
Actuarial loss (gain)		(34)	319
Curtailments		0	0
Contractual termination benefits		(1)	2
Currency translation		0	0
Defined Benefit Plan, Contributions by Plan Participants		31	40
Subsidy receipts		40	34
Benefits paid		(183)	(185)
Benefit obligations at end of year	1,674	1,887	1,957	1,674
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at beginning of year		415	447
Actual return on plan assets		3	26
Currency translation		0	0
Employer contributions		2	2
Benefits paid		(51)	(60)
Fair value of plan assets at end of year	$ 447	369	415	$ 447
Funded status at year end		$ (1,518)	$ (1,542)