Taxes on Earnings (Details) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Jul. 31, 2016 USD ($)	Jul. 31, 2015 USD ($)	Jul. 31, 2016 USD ($) county	Jul. 31, 2015 USD ($)	Oct. 31, 2015 USD ($)
Differences between the U.S. federal statutory income tax rate and HP's effective tax rate
Effective tax rate (as a percent)	5.60%	9.70%	7.40%	20.90%
U.S. federal statutory income tax rate (as a percent)			35.00%
Net income tax charges (benefits) related to discrete items	$ 37	$ (33)	$ (160)	$ (146)
Income tax charges for various prior period adjustments	61		22
Other benefits	131		305
Disposition of business	123		$ 123
Number of countries other than the United States where the entity is subject to income tax | county			105
Unrecognized tax benefits	11,100		$ 11,100		$ 4,900
Unrecognized tax benefits that would affect effective tax rate if realized	2,400		2,400		600
Increase in unrecognized tax benefits			6,200
Accrued income tax for interest and penalties	328		$ 328		269
Likelihood of no resolution period			12 months
Reasonably possible reduction in existing unrecognized tax benefits within the next 12 months	78		$ 78
Likelihood of conclusion period for certain federal, foreign and state tax issues			12 months
Current and long term deferred tax assets and liabilities
Long-term deferred tax assets	3,958		$ 3,958		3,925
Long-term deferred tax liabilities	(121)		(121)		(41)
Deferred tax assets net of deferred tax liabilities	$ 3,837		3,837		3,884
Advance royalty proceeds received from multi-year intercompany licensing arrangements			$ 3,700		$ 5,000
Royalty recognition term					5 years