Earnings per share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Oct. 28, 2011	Oct. 29, 2010	Oct. 28, 2011	Oct. 29, 2010
Net Income
Basic earnings	$ 171,164	$ 128,120	$ 474,175	$ 405,311
Diluted Earnings	$ 171,164	$ 128,120	$ 474,175	$ 405,311
Shares
Shares outstanding, basic (in shares)	341,955,000	341,062,000	341,670,000	340,961,000
Effect of dilutive share-based awards (in shares)	3,822,000	3,677,000	3,928,000	3,667,000
Shares outstanding, diluted (in shares)	345,777,000	344,739,000	345,598,000	344,628,000
Per Share Amount
Basic earnings per share (in dollars per share)	$ 0.50	$ 0.38	$ 1.39	$ 1.19
Diluted earnings per share (in dollars per share)	$ 0.50	$ 0.37	$ 1.37	$ 1.18
Shares of common stock outstanding excluded from computation of diluted earnings per share (in shares)	300,000	300,000