Financial Instruments - Cash Equivalents and Available-for-Sale Investments (Details) - USD ($) $ in Millions	Oct. 31, 2019	Oct. 31, 2018
Cash equivalents and available-for-sale investments
Cost	$ 3,705	$ 3,996
Fair Value	3,705	3,996
Available-for-Sale Investments:
Total available-for-sale investments, Cost	40	756
Total available-for-sale investments, Gross Unrealized Gain	16	11
Total available-for-sale investments, Gross Unrealized Loss	0	(3)
Total available-for-sale investments, Fair Value	56	764
Cost	3,745	4,752
Gross Unrealized Gain	16	11
Gross Unrealized Loss	0	(3)
Fair Value	3,761	4,760
Corporate Debt
Cash equivalents and available-for-sale investments
Cost	1,283	1,620
Fair Value	1,283	1,620
Available-for-Sale Investments:
Debt securities, Cost	0	368
Debt securities, Gross Unrealized Gain	0	0
Debt securities, Gross Unrealized Loss	0	(2)
Debt securities, Fair Value	0	366
Financial institution instruments
Cash equivalents and available-for-sale investments
Cost	0	9
Fair Value	0	9
Available-for-Sale Investments:
Debt securities, Cost	0	32
Debt securities, Gross Unrealized Gain	0	0
Debt securities, Gross Unrealized Loss	0	0
Debt securities, Fair Value	0	32
Government debt
Cash equivalents and available-for-sale investments
Cost	2,422	2,367
Fair Value	2,422	2,367
Available-for-Sale Investments:
Debt securities, Cost	0	314
Debt securities, Gross Unrealized Gain	0	0
Debt securities, Gross Unrealized Loss	0	(1)
Debt securities, Fair Value	0	313
Marketable equity securities and Mutual funds
Available-for-Sale Investments:
Equity securities, Cost	40	42
Equity securities, Gross Unrealized Gain	16	11
Equity securities, Gross Unrealized Loss	0	0
Equity securities, Fair Value	$ 56	$ 53

Cash Equivalents and Available For Sale Securities, Accumulated Gross Unrealized Gain, before Tax

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Cash Equivalents and Available For Sale Securities, Accumulated Gross Unrealized Loss, before Tax

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Cash Equivalents and Available For Sale Securities, Amortized Cost Basis

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Debt Securities, Trading, and Equity Securities, FV-NI, Accumulated Gross Unrealized Gain, before Tax

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Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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Amount of short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Excludes cash and cash equivalents within disposal group and discontinued operation.

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Cost of investment in debt investment in debt security measured at fair value with change in fair value recognized in net income (trading) and investment in equity security with change in fair value recognized in net income (FV-NI). Excludes equity method investment and investment in equity security without readily determinable fair value.

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