Segment Information - Segment Operating Results from Continuing Operations (Details) - USD ($) $ in Millions	3 Months Ended
	Jan. 31, 2018	Jan. 31, 2017
Segment Reporting Information [Line Items]
Net revenue	$ 7,674	$ 6,902
Segment earnings (loss) from continuing operations	261	453
Intersegment net revenue and other
Segment Reporting Information [Line Items]
Net revenue	164	246
Operating Segment
Segment Reporting Information [Line Items]
Net revenue	7,838	7,148
Segment earnings (loss) from continuing operations	677	792
Hybrid IT
Segment Reporting Information [Line Items]
Net revenue	6,176	5,536
Hybrid IT | Intersegment net revenue and other
Segment Reporting Information [Line Items]
Net revenue	155	219
Hybrid IT | Operating Segment
Segment Reporting Information [Line Items]
Net revenue	6,331	5,755
Segment earnings (loss) from continuing operations	608	733
Intelligent Edge
Segment Reporting Information [Line Items]
Net revenue	613	562
Intelligent Edge | Intersegment net revenue and other
Segment Reporting Information [Line Items]
Net revenue	7	8
Intelligent Edge | Operating Segment
Segment Reporting Information [Line Items]
Net revenue	620	570
Segment earnings (loss) from continuing operations	18	16
Financial Services
Segment Reporting Information [Line Items]
Net revenue	886	804
Financial Services | Intersegment net revenue and other
Segment Reporting Information [Line Items]
Net revenue	2	19
Financial Services | Operating Segment
Segment Reporting Information [Line Items]
Net revenue	888	823
Segment earnings (loss) from continuing operations	72	76
Corporate Investments
Segment Reporting Information [Line Items]
Net revenue	(1)	0
Corporate Investments | Intersegment net revenue and other
Segment Reporting Information [Line Items]
Net revenue	0	0
Corporate Investments | Operating Segment
Segment Reporting Information [Line Items]
Net revenue	(1)	0
Segment earnings (loss) from continuing operations	$ (21)	$ (33)