Segment reporting (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 30, 2015 USD ($) segment	Oct. 31, 2014 USD ($) segment	Oct. 30, 2015 USD ($) segment	Oct. 31, 2014 USD ($) segment
Segment reporting
Number of reportable segments | segment	1	1	1	1
Net sales data for classes of similar products
Net sales	$ 5,067,048	$ 4,724,409	$ 15,081,624	$ 13,970,529
Consumables
Net sales data for classes of similar products
Net sales	3,921,663	3,645,021	11,543,276	10,666,675
Seasonal
Net sales data for classes of similar products
Net sales	555,862	524,623	1,784,680	1,659,651
Home products
Net sales data for classes of similar products
Net sales	317,963	298,878	925,292	867,903
Apparel
Net sales data for classes of similar products
Net sales	$ 271,560	$ 255,887	$ 828,376	$ 776,300