Segment reporting (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 28, 2016 USD ($) segment	Oct. 30, 2015 USD ($) segment	Oct. 28, 2016 USD ($) segment	Oct. 30, 2015 USD ($) segment
Net sales data for classes of similar products
Net sales	$ 5,320,029	$ 5,067,048	$ 15,977,352	$ 15,081,624
Number of reportable segments
Number of reportable operating segments | segment	1	1	1	1
Consumables
Net sales data for classes of similar products
Net sales	$ 4,137,748	$ 3,921,663	$ 12,293,395	$ 11,543,276
Seasonal
Net sales data for classes of similar products
Net sales	575,912	555,862	1,873,715	1,784,680
Home products
Net sales data for classes of similar products
Net sales	329,715	317,963	968,161	925,292
Apparel
Net sales data for classes of similar products
Net sales	$ 276,654	$ 271,560	$ 842,081	$ 828,376