Financial Instruments - Schedule of Cash Equivalents and Available-for-Sale Investments (Details) - USD ($) $ in Millions	Jan. 31, 2018	Oct. 31, 2017
Cash Equivalents:
Cost	$ 4,013	$ 5,398
Fair Value	4,013	5,398
Available-for-Sale Investments:
Cost	1,316	1,194
Gross Unrealized Gain	12	17
Gross Unrealized Loss	(4)	(1)
Fair Value	1,324	1,210
Total cash equivalents and available-for-sale investments, Cost	5,329	6,592
Total cash equivalents and available-for-sale investments, Fair Value	5,337	6,608
Corporate debt
Cash Equivalents:
Cost	1,180	1,390
Fair Value	1,180	1,390
Available-for-Sale Investments:
Cost	669	629
Gross Unrealized Gain	0	0
Gross Unrealized Loss	(2)	0
Fair Value	667	629
Financial institution instruments
Cash Equivalents:
Cost	0	6
Fair Value	0	6
Available-for-Sale Investments:
Cost	77	78
Gross Unrealized Gain	0	0
Gross Unrealized Loss	0	0
Fair Value	77	78
Government debt
Cash Equivalents:
Cost	2,833	4,002
Fair Value	2,833	4,002
Available-for-Sale Investments:
Cost	524	443
Gross Unrealized Gain	0	0
Gross Unrealized Loss	(2)	(1)
Fair Value	522	442
Marketable equity securities
Available-for-Sale Investments:
Cost	4	5
Gross Unrealized Gain	2	7
Gross Unrealized Loss	0	0
Fair Value	6	12
Mutual funds
Available-for-Sale Investments:
Cost	42	39
Gross Unrealized Gain	10	10
Gross Unrealized Loss	0	0
Fair Value	$ 52	$ 49