Restructuring and Impairments - Restructuring Reserve by Type (Details) - USD ($) $ in Millions	3 Months Ended
	Jan. 31, 2018	Oct. 31, 2017	Jul. 31, 2017	Jan. 31, 2017	Jul. 31, 2014	Oct. 31, 2016
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ (3)	$ 6	$ 41	$ 7
Restructuring Reserve	8	15		11		$ 7
Restructuring and Related Cost, Incurred Cost	0			6
Payments for Restructuring	(4)			(2)
Restructuring Reserve, Accrual Adjustment	(3)			0
Employee Severance [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve	7	14		9		5
Restructuring and Related Cost, Incurred Cost	0			6
Payments for Restructuring	(4)			(2)
Restructuring Reserve, Accrual Adjustment	(3)			0
Lease Vacancy [Member] [Domain]
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve	0	0		1		1
Restructuring and Related Cost, Incurred Cost	0			0
Payments for Restructuring	0			0
Restructuring Reserve, Accrual Adjustment	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
Payments for Restructuring	0			0
Restructuring Reserve, Accrual Adjustment	$ 0			0
Other Postretirement Benefits Plan [Member] | Chatham [Member] | Facility Closing [Member]
Restructuring Cost and Reserve [Line Items]
Postemployment Benefits, Period Expense			$ 23	$ 6	$ 14