Financial Instruments - Schedule of Cash Equivalents and Available-for-Sale Investments (Details) - USD ($) $ in Millions	Apr. 30, 2018	Oct. 31, 2017
Cash Equivalents:
Cost	$ 2,667	$ 5,398
Fair Value	2,667	5,398
Available-for-Sale Investments:
Cost	1,133	1,194
Gross Unrealized Gain	12	17
Gross Unrealized Loss	(5)	(1)
Fair Value	1,140	1,210
Total cash equivalents and available-for-sale investments, Cost	3,800	6,592
Total cash equivalents and available-for-sale investments, Fair Value	3,807	6,608
Corporate debt
Cash Equivalents:
Cost	960	1,390
Fair Value	960	1,390
Available-for-Sale Investments:
Cost	557	629
Gross Unrealized Gain	0	0
Gross Unrealized Loss	(3)	0
Fair Value	554	629
Financial institution instruments
Cash Equivalents:
Cost	10	6
Fair Value	10	6
Available-for-Sale Investments:
Cost	66	78
Gross Unrealized Gain	0	0
Gross Unrealized Loss	0	0
Fair Value	66	78
Government debt
Cash Equivalents:
Cost	1,697	4,002
Fair Value	1,697	4,002
Available-for-Sale Investments:
Cost	465	443
Gross Unrealized Gain	0	0
Gross Unrealized Loss	(2)	(1)
Fair Value	463	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	41	39
Gross Unrealized Gain	10	10
Gross Unrealized Loss	0	0
Fair Value	$ 51	$ 49