Fair Value (Details) (USD $)	3 Months Ended	12 Months Ended				3 Months Ended	12 Months Ended
	Jul. 31, 2012	Oct. 31, 2012	Oct. 31, 2011	Oct. 31, 2012 Compaq	Oct. 31, 2012 Software	Oct. 31, 2012 Software Autonomy Acquisition	Oct. 31, 2012 Services	Oct. 31, 2012 Fair Value Measured Using Level 3 Compaq	Oct. 31, 2012 Fair Value Measured Using Level 3 Compaq Minimum Autonomy Acquisition	Oct. 31, 2012 Fair Value Measured Using Level 3 Compaq Maximum Autonomy Acquisition	Oct. 31, 2012 Fair Value Measured Using Level 3 Software Autonomy Acquisition	Oct. 31, 2012 Fair Value Measured Using Level 3 Services	Oct. 31, 2012 Fair Value, Measurements, Recurring Estimate of Fair Value, Fair Value Disclosure	Oct. 31, 2011 Fair Value, Measurements, Recurring Estimate of Fair Value, Fair Value Disclosure	Oct. 31, 2012 Fair Value, Measurements, Recurring Estimate of Fair Value, Fair Value Disclosure Time deposits	Oct. 31, 2011 Fair Value, Measurements, Recurring Estimate of Fair Value, Fair Value Disclosure Time deposits	Oct. 31, 2012 Fair Value, Measurements, Recurring Estimate of Fair Value, Fair Value Disclosure Money market funds	Oct. 31, 2011 Fair Value, Measurements, Recurring Estimate of Fair Value, Fair Value Disclosure Money market funds	Oct. 31, 2012 Fair Value, Measurements, Recurring Estimate of Fair Value, Fair Value Disclosure Marketable equity securities	Oct. 31, 2011 Fair Value, Measurements, Recurring Estimate of Fair Value, Fair Value Disclosure Marketable equity securities	Oct. 31, 2012 Fair Value, Measurements, Recurring Estimate of Fair Value, Fair Value Disclosure Foreign bonds	Oct. 31, 2011 Fair Value, Measurements, Recurring Estimate of Fair Value, Fair Value Disclosure Foreign bonds	Oct. 31, 2012 Fair Value, Measurements, Recurring Estimate of Fair Value, Fair Value Disclosure Corporate bonds and other debt securities	Oct. 31, 2011 Fair Value, Measurements, Recurring Estimate of Fair Value, Fair Value Disclosure Corporate bonds and other debt securities	Oct. 31, 2012 Fair Value, Measurements, Recurring Estimate of Fair Value, Fair Value Disclosure Interest rate contracts	Oct. 31, 2011 Fair Value, Measurements, Recurring Estimate of Fair Value, Fair Value Disclosure Interest rate contracts	Oct. 31, 2012 Fair Value, Measurements, Recurring Estimate of Fair Value, Fair Value Disclosure Foreign exchange contracts	Oct. 31, 2011 Fair Value, Measurements, Recurring Estimate of Fair Value, Fair Value Disclosure Foreign exchange contracts	Oct. 31, 2012 Fair Value, Measurements, Recurring Estimate of Fair Value, Fair Value Disclosure Other derivatives	Oct. 31, 2011 Fair Value, Measurements, Recurring Estimate of Fair Value, Fair Value Disclosure Other derivatives	Oct. 31, 2012 Fair Value, Measurements, Recurring Estimate of Fair Value, Fair Value Disclosure Mutual funds	Oct. 31, 2012 Fair Value, Measurements, Recurring Fair Value Measured Using Level 1	Oct. 31, 2011 Fair Value, Measurements, Recurring Fair Value Measured Using Level 1	Oct. 31, 2012 Fair Value, Measurements, Recurring Fair Value Measured Using Level 1 Money market funds	Oct. 31, 2011 Fair Value, Measurements, Recurring Fair Value Measured Using Level 1 Money market funds	Oct. 31, 2012 Fair Value, Measurements, Recurring Fair Value Measured Using Level 1 Marketable equity securities	Oct. 31, 2011 Fair Value, Measurements, Recurring Fair Value Measured Using Level 1 Marketable equity securities	Oct. 31, 2012 Fair Value, Measurements, Recurring Fair Value Measured Using Level 1 Foreign bonds	Oct. 31, 2011 Fair Value, Measurements, Recurring Fair Value Measured Using Level 1 Foreign bonds	Oct. 31, 2012 Fair Value, Measurements, Recurring Fair Value Measured Using Level 1 Corporate bonds and other debt securities	Oct. 31, 2011 Fair Value, Measurements, Recurring Fair Value Measured Using Level 1 Corporate bonds and other debt securities	Oct. 31, 2012 Fair Value, Measurements, Recurring Fair Value Measured Using Level 2	Oct. 31, 2011 Fair Value, Measurements, Recurring Fair Value Measured Using Level 2	Oct. 31, 2012 Fair Value, Measurements, Recurring Fair Value Measured Using Level 2 Time deposits	Oct. 31, 2011 Fair Value, Measurements, Recurring Fair Value Measured Using Level 2 Time deposits	Oct. 31, 2012 Fair Value, Measurements, Recurring Fair Value Measured Using Level 2 Marketable equity securities	Oct. 31, 2011 Fair Value, Measurements, Recurring Fair Value Measured Using Level 2 Marketable equity securities	Oct. 31, 2012 Fair Value, Measurements, Recurring Fair Value Measured Using Level 2 Foreign bonds	Oct. 31, 2011 Fair Value, Measurements, Recurring Fair Value Measured Using Level 2 Foreign bonds	Oct. 31, 2011 Fair Value, Measurements, Recurring Fair Value Measured Using Level 2 Corporate bonds and other debt securities	Oct. 31, 2012 Fair Value, Measurements, Recurring Fair Value Measured Using Level 2 Interest rate contracts	Oct. 31, 2011 Fair Value, Measurements, Recurring Fair Value Measured Using Level 2 Interest rate contracts	Oct. 31, 2012 Fair Value, Measurements, Recurring Fair Value Measured Using Level 2 Foreign exchange contracts	Oct. 31, 2011 Fair Value, Measurements, Recurring Fair Value Measured Using Level 2 Foreign exchange contracts	Oct. 31, 2012 Fair Value, Measurements, Recurring Fair Value Measured Using Level 2 Other derivatives	Oct. 31, 2011 Fair Value, Measurements, Recurring Fair Value Measured Using Level 2 Other derivatives	Oct. 31, 2012 Fair Value, Measurements, Recurring Fair Value Measured Using Level 2 Mutual funds	Oct. 31, 2012 Fair Value, Measurements, Recurring Fair Value Measured Using Level 3	Oct. 31, 2011 Fair Value, Measurements, Recurring Fair Value Measured Using Level 3	Oct. 31, 2012 Fair Value, Measurements, Recurring Fair Value Measured Using Level 3 Corporate bonds and other debt securities	Oct. 31, 2011 Fair Value, Measurements, Recurring Fair Value Measured Using Level 3 Corporate bonds and other debt securities	Oct. 31, 2012 Fair Value, Measurements, Recurring Fair Value Measured Using Level 3 Foreign exchange contracts	Oct. 31, 2011 Fair Value, Measurements, Recurring Fair Value Measured Using Level 3 Foreign exchange contracts	Oct. 31, 2011 Fair Value, Measurements, Recurring Fair Value Measured Using Level 3 Other derivatives
Financial assets and liabilities measured at fair value on a recurring basis
Total Assets, measured at fair value on a recurring basis													$ 9,869,000,000	$ 6,842,000,000	$ 3,641,000,000	$ 5,120,000,000	$ 4,630,000,000	$ 236,000,000	$ 63,000,000	$ 122,000,000	$ 385,000,000	$ 383,000,000	$ 45,000,000	$ 53,000,000	$ 344,000,000	$ 593,000,000	$ 291,000,000	$ 304,000,000	$ 1,000,000	$ 31,000,000	$ 469,000,000	$ 4,699,000,000	$ 366,000,000	$ 4,630,000,000	$ 236,000,000	$ 60,000,000	$ 120,000,000	$ 8,000,000	$ 7,000,000	$ 1,000,000	$ 3,000,000	$ 5,126,000,000	$ 6,387,000,000	$ 3,641,000,000	$ 5,120,000,000	$ 3,000,000	$ 2,000,000	$ 377,000,000	$ 376,000,000	$ 2,000,000	$ 344,000,000	$ 593,000,000	$ 291,000,000	$ 269,000,000	$ 1,000,000	$ 25,000,000	$ 469,000,000	$ 44,000,000	$ 89,000,000	$ 44,000,000	$ 48,000,000		$ 35,000,000	$ 6,000,000
Total Liabilities, measured at fair value on a recurring basis													518,000,000	904,000,000											29,000,000	71,000,000	486,000,000	832,000,000	3,000,000	1,000,000												517,000,000	895,000,000								29,000,000	71,000,000	485,000,000	823,000,000	3,000,000	1,000,000		1,000,000	9,000,000			1,000,000	9,000,000
Discount rate (as a percent)									11.00%	16.00%
Projected revenue growth rate (as a percent)									(61.00%)	13.00%
Impairment of goodwill		13,705,000,000	813,000,000		5,744,000,000		7,961,000,000					7,961,000,000
Impairment of goodwill and intangible assets		18,035,000,000	885,000,000			8,800,000,000					8,800,000,000
Amortizable purchased intangible assets, Impairment Loss				1,227,000,000				1,227,000,000
Amortizable purchased intangible assets, Impairment Loss	1,227,000,000	1,227,000,000		1,227,000,000
Fair Value and Carrying Value of Debt
Fair value, short- and long-term debt		28,400,000,000	31,100,000,000
Carrying value, short- and long-term debt		$ 28,400,000,000	$ 30,600,000,000