Acquisitions, Disposals and Related Items Acquisitions, Disposals and Related Items (Details) - USD ($) $ in Millions			3 Months Ended
	Aug. 10, 2016	Jun. 01, 2016	Jul. 31, 2017	Apr. 30, 2017	Oct. 31, 2016	Apr. 30, 2016	Jan. 31, 2017	Sep. 19, 2016
Significant Acquisitions and Disposals [Line Items]
Business acquisitions, net of cash acquired				$ 88		$ 0
Goodwill				17,575		16,751	$ 17,037
Net Income (Loss) Attributable to Parent				$ 3,039		$ 3,079
JD.com [Member]
Significant Acquisitions and Disposals [Line Items]
Available-for-sale Securities, Percent				5.00%
Purchase of available for sale securities					$ 1,900
Aggregate Ownership, Percent				10.00%
Yihaodian [Member]
Significant Acquisitions and Disposals [Line Items]
Gain (Loss) on Disposition of Assets		$ 535
Suburbia [Member]
Significant Acquisitions and Disposals [Line Items]
Proceeds from the disposal of certain operations	$ 1,000
Disposal Group, Including Discontinued Operation, Assets, Current					698
Disposal Group, Including Discontinued Operation, Liabilities, Current					$ 172
Yihaodian [Member]
Significant Acquisitions and Disposals [Line Items]
Noncash or Part Noncash Divestiture, Type of Consideration Received		Class A ordinary shares
Noncash or Part Noncash Divestiture, Amount of Consideration Received		$ 1,500
Noncash or Part Noncash Acquisition, Interest Acquired		5.00%
Jet.com [Member]
Significant Acquisitions and Disposals [Line Items]
Business acquisitions, net of cash acquired				$ 2,400
Goodwill								$ 1,700
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill								$ 600
Additional compensation over five year period				$ 800
Subsequent Event [Member] | Suburbia [Member]
Significant Acquisitions and Disposals [Line Items]
Gain (Loss) on Disposition of Business, Including Deferred Portion			$ 650
Gain (Loss) on Disposition of Business			$ 380
Gain Deferral Period			20 years
Net Income (Loss) Attributable to Parent			$ 160