Financial Instruments - Schedule of Cash Equivalents and Available-for-Sale Investments (Details) - USD ($) $ in Millions	Jul. 31, 2020	Oct. 31, 2019
Cash Equivalents:
Cost	$ 3,778	$ 3,705
Gross Unrealized Gain	0	0
Gross Unrealized Loss	0	0
Fair Value	3,778	3,705
Available-for-Sale Investments:
Equity securities, Fair Value	57	56
Cost	271	40
Gross Unrealized Gain	15	16
Gross Unrealized Loss	0	0
Fair Value	286	56
Total cash equivalents and available-for-sale investments, Cost	4,049	3,745
Total cash equivalents and available-for-sale investments, Gross Unrealized Gain	15	16
Total cash equivalents and available-for-sale investments, Gross Unrealized Loss	0	0
Total cash equivalents and available-for-sale investments, Fair Value	4,064	3,761
Corporate debt
Cash Equivalents:
Cost	985	1,283
Gross Unrealized Gain	0	0
Gross Unrealized Loss	0	0
Fair Value	985	1,283
Available-for-Sale Investments:
Debt securities, Cost	135	0
Debt securities, Gross Unrealized Gain	0	0
Debt securities, Gross Unrealized Loss	0	0
Debt securities, fair value	135	0
Financial Institution
Cash Equivalents:
Cost	13	0
Gross Unrealized Gain	0	0
Gross Unrealized Loss	0	0
Fair Value	13	0
Available-for-Sale Investments:
Debt securities, Cost	26	0
Debt securities, Gross Unrealized Gain	0	0
Debt securities, Gross Unrealized Loss	0	0
Debt securities, fair value	26	0
Government debt
Cash Equivalents:
Cost	2,780	2,422
Gross Unrealized Gain	0	0
Gross Unrealized Loss	0	0
Fair Value	2,780	2,422
Available-for-Sale Investments:
Debt securities, Cost	68	0
Debt securities, Gross Unrealized Gain	0	0
Debt securities, Gross Unrealized Loss	0	0
Debt securities, fair value	68	0
Marketable equity securities and mutual funds
Available-for-Sale Investments:
Equity securities, Cost	42	40
Equity securities, Gross Unrealized Gain	15	16
Equity securities, Gross Unrealized Loss	0	0
Equity securities, Fair Value	$ 57	$ 56