Segments and Disaggregated Revenue Revenue from Contract with Customer Excluding Assessed Tax, Sam's Club (Details) - Sam's Club $ in Millions	3 Months Ended
Apr. 30, 2018 USD ($)
Grocery and consumables [Member]
Revenue from External Customer [Line Items]
Revenue from contract with customer, excluding assessed tax	$ 8,012
Fuel, tobacco, and other categories [Member]
Revenue from External Customer [Line Items]
Revenue from contract with customer, excluding assessed tax	2,919
Home and apparel [Member]
Revenue from External Customer [Line Items]
Revenue from contract with customer, excluding assessed tax	1,202
Health and wellness [Member]
Revenue from External Customer [Line Items]
Revenue from contract with customer, excluding assessed tax	801
Technology, offices, and entertainment [Member]
Revenue from External Customer [Line Items]
Revenue from contract with customer, excluding assessed tax	688
Product and services, total [Member]
Revenue from External Customer [Line Items]
Revenue from contract with customer, excluding assessed tax	$ 13,622

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 32
-Paragraph 2A
-URI http://asc.fasb.org/extlink&oid=82859839&loc=SL82860478-203043

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=82913847&loc=SL49130543-203045

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=82913847&loc=SL49130539-203045

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=82913847&loc=SL49130545-203045

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