Financial Instruments - Cash Equivalents and Available-for-Sale Investments (Details) - USD ($) $ in Millions	Oct. 31, 2020	Oct. 31, 2019
Cash Equivalents:
Cost	$ 3,932	$ 3,705
Fair Value	3,932	3,705
Available-for-Sale Investments:
Total available-for-sale investments, Cost	316	40
Total available-for-sale investments, Gross Unrealized Gain	16	16
Total available-for-sale investments, Gross Unrealized Loss	0	0
Total available-for-sale investments, Fair Value	332	56
Cost	4,248	3,745
Gross Unrealized Gain	16	16
Gross Unrealized Loss	0	0
Fair Value	4,264	3,761
Corporate debt
Cash Equivalents:
Cost	1,700	1,283
Fair Value	1,700	1,283
Available-for-Sale Investments:
Debt securities, Cost	169	0
Debt securities, Gross Unrealized Gain	0	0
Debt securities, Gross Unrealized Loss	0	0
Debt securities, Fair Value	169	0
Financial institution instruments
Cash Equivalents:
Cost	59	0
Fair Value	59	0
Available-for-Sale Investments:
Debt securities, Cost	32	0
Debt securities, Gross Unrealized Gain	0	0
Debt securities, Gross Unrealized Loss	0	0
Debt securities, Fair Value	32	0
Government debt
Cash Equivalents:
Cost	2,173	2,422
Fair Value	2,173	2,422
Available-for-Sale Investments:
Debt securities, Cost	73	0
Debt securities, Gross Unrealized Gain	0	0
Debt securities, Gross Unrealized Loss	0	0
Debt securities, Fair Value	73	0
Marketable equity securities and Mutual funds
Available-for-Sale Investments:
Equity securities, Cost	42	40
Equity securities, Gross Unrealized Gain	16	16
Equity securities, Gross Unrealized Loss	0	0
Equity securities, Fair Value	$ 58	$ 56