Taxes on Earnings (Details) $ in Millions	3 Months Ended			9 Months Ended		12 Months Ended
	Jul. 31, 2015 USD ($)	Jan. 31, 2015 USD ($)	Jul. 31, 2014 USD ($)	Jul. 31, 2015 USD ($) country item	Jul. 31, 2014 USD ($)	Oct. 31, 2014 USD ($)
Differences between the U.S. federal statutory income tax rate and HP's effective tax rate
Effective tax rate (as a percent)	22.60%		25.00%	22.00%	23.20%
U.S. federal statutory income tax rate (as a percent)				35.00%
Net tax charges (benefits) related to discrete items	$ (164)		$ (88)	$ (349)	$ (53)
Tax benefits from separation costs	122			237
Tax benefits from restructuring and acquisition charges	23			75
Tax benefits from restructuring charges			$ 100		$ 145
Tax benefit from the retroactive research and development credit				47
Various tax charges (benefits) related to discrete items	(19)			$ 10
Number of countries other than the United States where the entity is subject to income tax | country				105
Income tax examination, proposed assessment amount	680			$ 680
Unrecognized Tax Benefits	11,100			11,100		$ 4,100
Unrecognized tax benefits that would affect effective tax rate if realized	2,400			2,400		2,200
Increase in unrecognized tax benefits				7,000
Accrued income tax payable for interest and penalties	254			$ 254
Likelihood of no resolution period				12 months
Likelihood of conclusion period for certain federal, foreign and state tax issues				12 months
Reasonably possible reduction in existing unrecognized tax benefits within the next 12 months	1,100			$ 1,100
Current and long term deferred tax assets and liabilities
Current deferred tax assets	3,242			3,242		2,754
Current deferred tax liabilities	(216)			(216)		(284)
Long-term deferred tax assets	899			899		740
Long-term deferred tax liabilities	(2,965)			(2,965)		(1,124)
Net deferred tax assets net of deferred tax liabilities	$ 960			$ 960		2,086
Advance royalty proceeds received from intercompany advanced royalty payments and licensing arrangements		$ 8,200				11,500
Recognition of net long term deferred tax assets from intercompany licensing arrangement		$ 2,100				$ 1,700
Royalty recognition term		5 years				15 years
Number of independent publicly-traded companies | item				2