Financial Instruments - Schedule of Cash Equivalents and Available-for-Sale Investments (Details) - USD ($) $ in Millions	Jul. 31, 2018	Oct. 31, 2017
Cash Equivalents:
Cost	$ 5,035	$ 5,398
Fair Value	5,035	5,398
Available-for-Sale Investments:
Cost	935	1,194
Gross Unrealized Gain	12	17
Gross Unrealized Loss	(4)	(1)
Gross Unrealized Gain	12	17
Gross Unrealized Loss	(4)	(1)
Fair Value	943	1,210
Total cash equivalents and available-for-sale investments, Cost	5,970	6,592
Total cash equivalents and available-for-sale investments, Fair Value	5,978	6,608
Corporate debt
Cash Equivalents:
Cost	1,493	1,390
Fair Value	1,493	1,390
Available-for-Sale Investments:
Cost	436	629
Gross Unrealized Gain	0	0
Gross Unrealized Loss	(2)	0
Fair Value	434	629
Financial institution instruments
Cash Equivalents:
Cost	0	6
Fair Value	0	6
Available-for-Sale Investments:
Cost	39	78
Gross Unrealized Gain	0	0
Gross Unrealized Loss	0	0
Fair Value	39	78
Government debt
Cash Equivalents:
Cost	3,542	4,002
Fair Value	3,542	4,002
Available-for-Sale Investments:
Cost	415	443
Gross Unrealized Gain	0	0
Gross Unrealized Loss	(2)	(1)
Fair Value	413	442
Marketable equity securities
Available-for-Sale Investments:
Cost	4	5
Gross Unrealized Gain	3	7
Gross Unrealized Loss	0	0
Fair Value	7	12
Mutual funds
Available-for-Sale Investments:
Cost	41	39
Gross Unrealized Gain	9	10
Gross Unrealized Loss	0	0
Fair Value	$ 50	$ 49