Segment Information - Segment Operating Results from Continuing Operations (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Apr. 30, 2020	Apr. 30, 2019	Apr. 30, 2020	Apr. 30, 2019
Segment Reporting Information [Line Items]
Net revenue	$ 6,009	$ 7,150	$ 12,958	$ 14,703
Segment earnings (loss) from operations	(834)	434	(486)	890
Intersegment net revenue and other
Segment Reporting Information [Line Items]
Net revenue	(165)	(173)	(243)	(313)
Operating Segment
Segment Reporting Information [Line Items]
Net revenue	6,174	7,323	13,201	15,016
Segment earnings (loss) from operations	425	713	1,100	1,446
Compute
Segment Reporting Information [Line Items]
Net revenue	2,534	3,193	5,497	6,702
Compute | Intersegment net revenue and other
Segment Reporting Information [Line Items]
Net revenue	(106)	(125)	(154)	(191)
Compute | Operating Segment
Segment Reporting Information [Line Items]
Net revenue	2,640	3,318	5,651	6,893
Segment earnings (loss) from operations	125	307	411	647
HPC & MCS
Segment Reporting Information [Line Items]
Net revenue	564	696	1,380	1,424
HPC & MCS | Intersegment net revenue and other
Segment Reporting Information [Line Items]
Net revenue	(25)	(25)	(32)	(76)
HPC & MCS | Operating Segment
Segment Reporting Information [Line Items]
Net revenue	589	721	1,412	1,500
Segment earnings (loss) from operations	33	92	82	190
Storage
Segment Reporting Information [Line Items]
Net revenue	1,060	1,303	2,295	2,640
Storage | Intersegment net revenue and other
Segment Reporting Information [Line Items]
Net revenue	(26)	(15)	(41)	(34)
Storage | Operating Segment
Segment Reporting Information [Line Items]
Net revenue	1,086	1,318	2,336	2,674
Segment earnings (loss) from operations	145	244	371	498
A & PS
Segment Reporting Information [Line Items]
Net revenue	236	258	478	497
A & PS | Intersegment net revenue and other
Segment Reporting Information [Line Items]
Net revenue	(1)	(2)	(2)	(4)
A & PS | Operating Segment
Segment Reporting Information [Line Items]
Net revenue	237	260	480	501
Segment earnings (loss) from operations	2	(14)	0	(46)
Intelligent Edge
Segment Reporting Information [Line Items]
Net revenue	661	681	1,376	1,387
Intelligent Edge | Intersegment net revenue and other
Segment Reporting Information [Line Items]
Net revenue	(4)	(4)	(9)	(3)
Intelligent Edge | Operating Segment
Segment Reporting Information [Line Items]
Net revenue	665	685	1,385	1,390
Segment earnings (loss) from operations	73	36	143	60
Financial Services
Segment Reporting Information [Line Items]
Net revenue	830	894	1,687	1,810
Financial Services | Intersegment net revenue and other
Segment Reporting Information [Line Items]
Net revenue	(3)	(2)	(5)	(5)
Financial Services | Operating Segment
Segment Reporting Information [Line Items]
Net revenue	833	896	1,692	1,815
Segment earnings (loss) from operations	75	77	148	154
Corporate Investments
Segment Reporting Information [Line Items]
Net revenue	124	125	245	243
Corporate Investments | Intersegment net revenue and other
Segment Reporting Information [Line Items]
Net revenue	0	0	0	0
Corporate Investments | Operating Segment
Segment Reporting Information [Line Items]
Net revenue	124	125	245	243
Segment earnings (loss) from operations	$ (28)	$ (29)	$ (55)	$ (57)