Overview and Basis of Presentation - Effects of New Accounting Standards (Details) - USD ($) $ in Millions	Jan. 31, 2019		Nov. 01, 2018	Oct. 31, 2018		Jan. 31, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Accounts receivable	$ 3,183	[1]	$ 3,301	$ 3,263	[1]	$ 3,263
Inventory	2,300		2,433	2,447
Other current assets	2,667		3,330	3,280
Long-term financing receivables and other assets	9,438		11,403	11,359
Total assets	51,758		20,467	55,493
Taxes on earnings	295		388	378
Deferred revenue	3,152		3,141	3,177
Other accrued liabilities	3,769		3,871	3,840
Other non-current liabilities	6,684		6,855	6,885
Subtotal liabilities			14,255
Accumulated deficit	(8,034)		(5,756)	(5,899)
Subtotal stockholders' equity	18,293		(5,756)	21,239
Total liabilities and stockholders' equity	$ 51,758		8,499	55,493
Previously Reported [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Accounts receivable				3,263
Inventory				2,447
Other current assets				3,280
Long-term financing receivables and other assets				11,359
Total assets				20,349
Taxes on earnings				378
Deferred revenue				3,177
Other accrued liabilities				3,840
Other non-current liabilities				6,885
Subtotal liabilities				14,280
Accumulated deficit				(5,899)
Subtotal stockholders' equity				(5,899)
Total liabilities and stockholders' equity				$ 8,381
Difference between Revenue Guidance in Effect before and after Topic 606 [Member] | Restatement Adjustment [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Accounts receivable			38
Inventory			(14)
Other current assets			50
Long-term financing receivables and other assets			44
Total assets			118
Taxes on earnings			10
Deferred revenue			(36)
Other accrued liabilities			31
Other non-current liabilities			(30)
Subtotal liabilities			(25)
Accumulated deficit			143
Subtotal stockholders' equity			143
Total liabilities and stockholders' equity			$ 118

[1] The allowance for doubtful accounts related to accounts receivable was $37 million and $39 million at January 31, 2019 and October 31, 2018, respectively.