Segment Information - Segment Operating Results from Continuing Operations (Details) - USD ($) $ in Millions	3 Months Ended
	Jan. 31, 2019	Jan. 31, 2018
Segment Reporting Information [Line Items]
Net revenue	$ 7,553	$ 7,674
Segment earnings (loss) from continuing operations	456	228
Intersegment net revenue and other
Segment Reporting Information [Line Items]
Net revenue	140	164
Operating Segment
Segment Reporting Information [Line Items]
Net revenue	7,693	7,838
Segment earnings (loss) from continuing operations	733	651
Hybrid IT
Segment Reporting Information [Line Items]
Net revenue	5,832	6,000
Hybrid IT | Intersegment net revenue and other
Segment Reporting Information [Line Items]
Net revenue	138	158
Hybrid IT | Operating Segment
Segment Reporting Information [Line Items]
Net revenue	5,970	6,158
Segment earnings (loss) from continuing operations	675	572
Intelligent Edge
Segment Reporting Information [Line Items]
Net revenue	687	652
Intelligent Edge | Intersegment net revenue and other
Segment Reporting Information [Line Items]
Net revenue	(1)	4
Intelligent Edge | Operating Segment
Segment Reporting Information [Line Items]
Net revenue	686	656
Segment earnings (loss) from continuing operations	9	34
Financial Services
Segment Reporting Information [Line Items]
Net revenue	916	886
Financial Services | Intersegment net revenue and other
Segment Reporting Information [Line Items]
Net revenue	3	2
Financial Services | Operating Segment
Segment Reporting Information [Line Items]
Net revenue	919	888
Segment earnings (loss) from continuing operations	77	71
Corporate Investments
Segment Reporting Information [Line Items]
Net revenue	118	136
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	118	136
Segment earnings (loss) from continuing operations	$ (28)	$ (26)