Common stock transactions (Details) (Common Stock, Pursuant to Authorized Repurchase Program, USD $) Share data in Millions, unless otherwise specified	6 Months Ended
Aug. 01, 2014	Aug. 02, 2013
Common Stock \| Pursuant to Authorized Repurchase Program
Common stock transactions
Common stock repurchase authorization	$ 2,000,000,000
Remaining authorization available under the common stock repurchase program	223,400,000
Shares acquired under share repurchase program	14.1	4.3
Aggregate purchase price	$ 800,100,000	$ 220,000,000

Equity impact of the value of stock that has been repurchased during the period and has not been retired and is not held in treasury. Some state laws may mandate the circumstances under which an entity may acquire its own stock and prescribe the accounting treatment therefore. This element is used when state law does not recognize treasury stock.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Article 3

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 10

-Section 50

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21463-112644

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 29, 30, 31

-Article 5

Name:	us-gaap_StockRepurchasedDuringPeriodValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration