Restructuring and Impairments - Restructuring Reserve by Type (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Oct. 31, 2015	Jul. 31, 2015	Oct. 31, 2018	Oct. 31, 2017	Oct. 31, 2016
Restructuring Cost and Reserve [Line Items]
Restructuring charges			$ (1)	$ 3	$ 10
Restructuring Reserve	$ 68		4	15	7
Restructuring and Related Cost, Incurred Cost			3	22	4
Payments for Restructuring			(10)	(13)	(67)
Restructuring Reserve, Accrual Adjustment			(4)	(1)	2
Employee Severance [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges	10	$ 13
Restructuring Reserve	62		3	14	5
Restructuring and Related Cost, Incurred Cost			3	22	4
Payments for Restructuring			(10)	(12)	(63)
Restructuring Reserve, Accrual Adjustment			(4)	(1)	2
Lease Vacancy [Member] [Domain]
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve	5		0	0	1
Restructuring and Related Cost, Incurred Cost			0	0	0
Payments for Restructuring			0	(1)	(4)
Restructuring Reserve, Accrual Adjustment			0	0	0
Other Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve	$ 1		1	1	1
Restructuring and Related Cost, Incurred Cost			0	0	0
Payments for Restructuring			0	0	0
Restructuring Reserve, Accrual Adjustment			$ 0	$ 0	$ 0