Acquisitions, Disposals and Related Items Acquisitions, Disposals and Related Items (Details) - USD ($) $ in Millions				3 Months Ended	9 Months Ended
	Aug. 10, 2016	Jun. 01, 2016	Jul. 01, 2015	Oct. 31, 2016	Oct. 31, 2016	Oct. 31, 2015	Sep. 19, 2016	Jan. 31, 2016
Significant Acquisitions and Disposals [Line Items]
Available-for-sale Securities, Noncurrent					$ 1,901	$ 0
Proceeds from the disposal of certain operations					0	246
Payments to Acquire Businesses, Net of Cash Acquired					2,406	0
Goodwill				$ 17,792	$ 17,792	$ 17,051		$ 16,695
JD.com [Member]
Significant Acquisitions and Disposals [Line Items]
Available-for-sale Securities, Noncurrent				$ 1,900
Available-for-sale Securities, Percent				5.00%	5.00%
Aggregate Ownership, Percent				10.00%	10.00%
Yihaodian [Member]
Significant Acquisitions and Disposals [Line Items]
Purchase of interests of noncontrolling interest			$ 760
Gain (Loss) on Disposition of Business		$ 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				$ 591	$ 591
Disposal Group, Including Discontinued Operation, Liabilities, Current				163	163
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 Acquisition, Interest Acquired		5.00%
Noncash or Part Noncash Divestiture, Amount of Consideration Received		$ 1,500
Jet.com [Member]
Significant Acquisitions and Disposals [Line Items]
Payments to Acquire Businesses, Net of Cash Acquired					2,400
Goodwill							$ 1,700
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill							$ 600
Contractual Obligation				$ 800	$ 800