Restructuring Charges (Details) (USD $)	3 Months Ended	6 Months Ended		6 Months Ended	12 Months Ended	3 Months Ended	6 Months Ended	1 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended		6 Months Ended	1 Months Ended	6 Months Ended		1 Months Ended	3 Months Ended	6 Months Ended	1 Months Ended	6 Months Ended		3 Months Ended	6 Months Ended
	Apr. 30, 2012	Apr. 30, 2012	Oct. 31, 2011	Apr. 30, 2012 Fiscal 2010 Acquisitions	Oct. 31, 2011 Fiscal 2010 Acquisitions	Apr. 30, 2012 Fiscal 2010 ES Restructuring Plan	Apr. 30, 2012 Fiscal 2010 ES Restructuring Plan	Jun. 30, 2010 Fiscal 2010 ES Restructuring Plan Severance position	Jan. 31, 2012 Fiscal 2010 ES Restructuring Plan Severance	Apr. 30, 2012 Fiscal 2010 ES Restructuring Plan Severance position	Apr. 30, 2012 Fiscal 2010 ES Restructuring Plan Infrastructure	Jan. 31, 2012 Fiscal 2010 ES Restructuring Plan Infrastructure	Apr. 30, 2012 Fiscal 2010 ES Restructuring Plan Infrastructure	May 31, 2009 Fiscal 2009 Restructuring Plan position	Apr. 30, 2012 Fiscal 2009 Restructuring Plan	Oct. 31, 2011 Fiscal 2009 Restructuring Plan position	Aug. 31, 2008 Fiscal 2008 HP/EDS Restructuring Plan	Apr. 30, 2012 Fiscal 2008 HP/EDS Restructuring Plan	Apr. 30, 2012 Fiscal 2008 HP/EDS Restructuring Plan	Aug. 31, 2008 Fiscal 2008 HP/EDS Restructuring Plan Severance position	Apr. 30, 2012 Fiscal 2008 HP/EDS Restructuring Plan Severance	Oct. 31, 2011 Fiscal 2008 HP/EDS Restructuring Plan Severance position	Apr. 30, 2012 Fiscal 2008 HP/EDS Restructuring Plan Infrastructure	Apr. 30, 2012 Fiscal 2008 HP/EDS Restructuring Plan Infrastructure
Restructuring and related costs
Additional restructuring costs					$ 33,000,000
Expected positions to be eliminated								8,000						4,400						25,000
Positions eliminated										7,000						4,400						25,000
Implementation period (in years)																	4 years
Costs reflected in purchase price of Electronic Data Systems Corporation ("EDS")																	1,500,000,000
Restructuring Reserve
Balance at the beginning of the period		813,000,000		59,000,000			496,000,000		493,000,000	493,000,000		3,000,000	3,000,000						258,000,000					258,000,000
Charges	53,000,000	93,000,000				35,000,000	39,000,000		(100,000,000)	(100,000,000)	35,000,000	104,000,000	139,000,000		7,000,000			18,000,000	47,000,000		5,000,000		18,000,000	42,000,000
Cash payments		(274,000,000)		(18,000,000)			(176,000,000)			(72,000,000)			(104,000,000)		(8,000,000)				(72,000,000)		(6,000,000)			(66,000,000)
Non-cash settlements and other adjustments		(58,000,000)					(53,000,000)			(16,000,000)			(37,000,000)		1,000,000				(6,000,000)		1,000,000			(7,000,000)
Balance at the end of the period	574,000,000	574,000,000		41,000,000	59,000,000	306,000,000	306,000,000			305,000,000	1,000,000		1,000,000					227,000,000	227,000,000				227,000,000	227,000,000
Total costs and adjustments to date		4,581,000,000		114,000,000			955,000,000			623,000,000			332,000,000		301,000,000				3,211,000,000		2,195,000,000			1,016,000,000
Total expected costs and adjustments		4,694,000,000		121,000,000	121,000,000		992,000,000			623,000,000			369,000,000		301,000,000				3,280,000,000		2,195,000,000			1,085,000,000
Long-term portion of restructuring reserve, recorded in Other liabilities	301,000,000	301,000,000	159,000,000
Expected cost of the plan								1,000,000,000						301,000,000			3,300,000,000
Short-term portion of restructuring reserve, recorded in Accrued restructuring	$ 273,000,000	$ 273,000,000	$ 654,000,000