Stock-Based Compensation - Stock-Based Compensation Expense (Narrative) (Details) - USD ($)	3 Months Ended		9 Months Ended
	Jul. 31, 2017	Jul. 31, 2016	Jul. 31, 2017	Jul. 31, 2016
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Pre-tax expense recorded within Separation costs	$ 186,000,000	$ 76,000,000	$ 412,000,000	$ 246,000,000
Restructuring charges	165,000,000	93,000,000	399,000,000	346,000,000
Discontinued operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Stock-based compensation expense	0	32,000,000	100,000,000	105,000,000
Continuing operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Stock-based compensation expense	128,000,000	117,000,000	406,000,000	347,000,000
Everett Transaction
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Stock-based compensation expense	5,000,000		100,000,000
The Plan
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Pre-tax expense recorded within Separation costs	7,000,000	$ 12,000,000	40,000,000
Restructuring charges	10,000,000		29,000,000	$ 5,000,000
SGI | The Plan
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Restructuring charges	14,000,000		21,000,000
Net loss from discontinued operations | Discontinued operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Stock-based compensation expense	0		69,000,000
Separation costs | Continuing operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Stock-based compensation expense	$ 5,000,000		$ 31,000,000