Taxes on Earnings - Uncertain Tax Positions (Narrative) (Details) $ in Millions	12 Months Ended
	Oct. 31, 2018 USD ($) country	Oct. 31, 2017 USD ($)	Oct. 31, 2016 USD ($)	Oct. 31, 2015 USD ($)
Income Tax Disclosure [Abstract]
Unrecognized tax benefits	$ 7,771	$ 10,808	$ 10,858	$ 6,546
Unrecognized tax benefits that would affect effective tax rate if realized	1,500	3,900
Decrease in unrecognized tax benefits	3,000
Accrued income tax for interest and penalties	$ 160	$ 257	$ 193
Likelihood of no resolution period	12 months
Conclusion of federal, foreign and state tax issues, period	12 months
Reasonably possible decrease in existing unrecognized tax benefits within the next 12 months	$ 6,400
Reasonably possible decrease in associated gain contingencies within the next 12 months	$ 740
Number of other countries in which HP is subject to income taxes | country	60
Undistributed earnings from non-U.S. operations	$ 5,400