Segment Information - Subsegments (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Apr. 30, 2017	Apr. 30, 2016	Apr. 30, 2017	Apr. 30, 2016
Segment Reporting Information
Net revenue	$ (7,445)	$ (8,509)	$ (15,001)	$ (17,041)
Operating segments
Segment Reporting Information
Net revenue	(7,800)	(8,893)	(15,669)	(17,807)
Elimination of intersegment net revenue and other
Segment Reporting Information
Net revenue	(355)	(384)	(668)	(766)
Enterprise Group
Segment Reporting Information
Net revenue	(5,943)	(6,870)	(12,041)	(13,752)
Enterprise Group | Operating segments
Segment Reporting Information
Net revenue	(6,243)	(7,159)	(12,568)	(14,341)
Enterprise Group | Operating segments | Servers
Segment Reporting Information
Net revenue	(2,991)	(3,498)	(6,094)	(7,034)
Enterprise Group | Operating segments | Technology Services
Segment Reporting Information
Net revenue	(1,971)	(2,019)	(3,914)	(4,004)
Enterprise Group | Operating segments | Storage
Segment Reporting Information
Net revenue	(699)	(808)	(1,429)	(1,645)
Enterprise Group | Operating segments | Networking
Segment Reporting Information
Net revenue	(582)	(834)	(1,131)	(1,658)
Enterprise Group | Elimination of intersegment net revenue and other
Segment Reporting Information
Net revenue	(300)	(289)	(527)	(589)
Software
Segment Reporting Information
Net revenue	(637)	(703)	(1,291)	(1,423)
Software | Operating segments
Segment Reporting Information
Net revenue	(685)	(774)	(1,406)	(1,554)
Software | Elimination of intersegment net revenue and other
Segment Reporting Information
Net revenue	(48)	(71)	(115)	(131)
Financial Services
Segment Reporting Information
Net revenue	(865)	(764)	(1,669)	(1,518)
Financial Services | Operating segments
Segment Reporting Information
Net revenue	(872)	(788)	(1,695)	(1,564)
Financial Services | Elimination of intersegment net revenue and other
Segment Reporting Information
Net revenue	(7)	(24)	(26)	(46)
Corporate Investments
Segment Reporting Information
Net revenue	0	(172)	0	(348)
Corporate Investments | Operating segments
Segment Reporting Information
Net revenue	0	(172)	0	(348)
Corporate Investments | Elimination of intersegment net revenue and other
Segment Reporting Information
Net revenue	$ 0	$ 0	$ 0	$ 0