Segment Information (Detail 2) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Oct. 31, 2019	Jul. 31, 2019	Apr. 30, 2019	Jan. 31, 2019	Oct. 31, 2018	Jul. 31, 2018	Apr. 30, 2018	Jan. 31, 2018	Oct. 31, 2019	Oct. 31, 2018	Oct. 31, 2017
Segment Reporting Information
Net revenue	$ 7,215	$ 7,217	$ 7,150	$ 7,553	$ 7,946	$ 7,764	$ 7,468	$ 7,674	$ 29,135	$ 30,852	$ 28,871
Segment earnings (loss) from operations	$ 460	$ (76)	$ 434	$ 456	$ 653	$ 490	$ 366	$ 228	1,274	1,737	564
Hybrid IT
Segment Reporting Information
Net revenue									22,230	23,750	22,063
Intelligent Edge
Segment Reporting Information
Net revenue									2,828	2,903	2,680
Financial Services
Segment Reporting Information
Net revenue									3,570	3,656	3,574
Corporate Investments
Segment Reporting Information
Net revenue									507	543	554
Intersegment Eliminations
Segment Reporting Information
Net revenue									(615)	(780)	(945)
Intersegment Eliminations | Hybrid IT
Segment Reporting Information
Net revenue									(595)	(748)	(876)
Intersegment Eliminations | Intelligent Edge
Segment Reporting Information
Net revenue									(9)	(17)	(42)
Intersegment Eliminations | Financial Services
Segment Reporting Information
Net revenue									(11)	(15)	(28)
Intersegment Eliminations | Corporate Investments
Segment Reporting Information
Net revenue									0	0	1
Operating segments
Segment Reporting Information
Net revenue									29,750	31,632	29,816
Segment earnings (loss) from operations									3,096	2,975	2,684
Operating segments | Hybrid IT
Segment Reporting Information
Net revenue									22,825	24,498	22,939
Segment earnings (loss) from operations									2,804	2,503	2,183
Operating segments | Intelligent Edge
Segment Reporting Information
Net revenue									2,837	2,920	2,722
Segment earnings (loss) from operations									95	277	291
Operating segments | Financial Services
Segment Reporting Information
Net revenue									3,581	3,671	3,602
Segment earnings (loss) from operations									305	286	301
Operating segments | Corporate Investments
Segment Reporting Information
Net revenue									507	543	553
Segment earnings (loss) from operations									$ (108)	$ (91)	$ (91)