Segment reporting (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Oct. 31, 2014 segment	Nov. 01, 2013 segment	Oct. 31, 2014 segment	Nov. 01, 2013 segment
Segment reporting
Number of reportable segments	1	1	1	1
Net sales data for classes of similar products
Net sales	$ 4,724,409	$ 4,381,838	$ 13,970,529	$ 13,010,222
Consumables
Net sales data for classes of similar products
Net sales	3,645,021	3,362,796	10,666,675	9,859,528
Seasonal
Net sales data for classes of similar products
Net sales	524,623	505,793	1,659,651	1,610,965
Home products
Net sales data for classes of similar products
Net sales	298,878	276,770	867,903	807,986
Apparel
Net sales data for classes of similar products
Net sales	$ 255,887	$ 236,479	$ 776,300	$ 731,743