Restructuring - Schedule of Restructuring Activities (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Apr. 30, 2018	Apr. 30, 2017	Apr. 30, 2018	Apr. 30, 2017
Restructuring Reserve
Charges	$ 9	$ 69	$ 12	$ 152
Cash payments			(414)	$ (545)
Total
Restructuring Reserve
Balance at the beginning of the period			254
Charges			12
Cash payments			(152)
Non-cash items			5
Balance at the end of the period	119		119
Total costs incurred to date, as of April 30, 2018	2,235		2,235
Total costs expected to be incurred, as of April 30, 2018	2,235		2,235
Employee Severance | 2015 Plan
Restructuring Reserve
Balance at the beginning of the period			219
Charges			3
Cash payments			(136)
Non-cash items			1
Balance at the end of the period	87		87
Total costs incurred to date, as of April 30, 2018	745		745
Total costs expected to be incurred, as of April 30, 2018	745		745
Infrastructure and other | 2015 Plan
Restructuring Reserve
Balance at the beginning of the period			17
Charges			(1)
Cash payments			(6)
Non-cash items			3
Balance at the end of the period	13		13
Total costs incurred to date, as of April 30, 2018	79		79
Total costs expected to be incurred, as of April 30, 2018	79		79
Infrastructure and other | 2012 Plan
Restructuring Reserve
Balance at the beginning of the period			2
Charges			(1)
Cash payments			0
Non-cash items			0
Balance at the end of the period	1		1
Total costs incurred to date, as of April 30, 2018	145		145
Total costs expected to be incurred, as of April 30, 2018	145		145
Employee Severance and EER | 2012 Plan
Restructuring Reserve
Balance at the beginning of the period			16
Charges			11
Cash payments			(10)
Non-cash items			1
Balance at the end of the period	18		18
Total costs incurred to date, as of April 30, 2018	1,266		1,266
Total costs expected to be incurred, as of April 30, 2018	$ 1,266		$ 1,266