Taxes on Earnings - Uncertain Tax Positions (Narrative) (Details) $ in Millions	12 Months Ended
	Oct. 31, 2019 USD ($) country	Oct. 31, 2018 USD ($)	Oct. 31, 2017 USD ($)	Oct. 31, 2016 USD ($)
Income Tax Disclosure [Abstract]
Unrecognized tax benefits	$ 929	$ 7,771	$ 10,808	$ 10,858
Unrecognized tax benefits that would affect effective tax rate if realized	803	1,500
Decrease in unrecognized tax benefits	6,800
Accrued income tax for interest and penalties	$ 56	$ 160	$ 257
Likelihood of no resolution period	12 months
Number of other countries in which HP is subject to income taxes | country	58
Undistributed earnings from non-U.S. operations	$ 5,700