Quarterly financial data (unaudited) (Details) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Jan. 31, 2020 USD ($) item $ / shares	Nov. 01, 2019 USD ($) item $ / shares	Aug. 02, 2019 USD ($) item $ / shares	May 03, 2019 USD ($) item $ / shares	Feb. 01, 2019 USD ($) item $ / shares	Nov. 02, 2018 USD ($) item $ / shares	Aug. 03, 2018 USD ($) item $ / shares	May 04, 2018 USD ($) item $ / shares	Jan. 31, 2020 USD ($) $ / shares	Feb. 01, 2019 USD ($) $ / shares	Feb. 02, 2018 USD ($) $ / shares
Selected unaudited quarterly financial data
Number of weeks in a quarter | item	13	13	13	13	13	13	13	13
Net sales	$ 7,157,642	$ 6,991,393	$ 6,981,753	$ 6,623,185	$ 6,649,809	$ 6,417,462	$ 6,443,309	$ 6,114,463	$ 27,753,973	$ 25,625,043	$ 23,470,967
Gross profit	2,272,763	2,065,086	2,148,936	2,002,276	2,071,689	1,895,059	1,974,873	1,862,249	8,489,061	7,803,870	7,221,359
Operating profit	720,875	491,417	577,775	512,237	638,503	442,143	545,476	490,184	2,302,304	2,116,306	2,007,818
Net income	$ 535,437	$ 365,550	$ 426,555	$ 385,013	$ 483,241	$ 334,142	$ 407,237	$ 364,852	$ 1,712,555	$ 1,589,472	$ 1,538,960
Basic earnings per share (in dollars per share) | $ / shares	$ 2.11	$ 1.43	$ 1.65	$ 1.49	$ 1.85	$ 1.26	$ 1.53	$ 1.36	$ 6.68	$ 5.99	$ 5.64
Diluted earnings per share (in dollars per share) | $ / shares	$ 2.10	$ 1.42	$ 1.65	$ 1.48	$ 1.84	$ 1.26	$ 1.52	$ 1.36	$ 6.64	$ 5.97	$ 5.63
Legal fees			$ 31,000
Leagl fees, net of tax			$ 24,100
Effect of legal expenses on earnings per diluted share (in dollars per share) | $ / shares			$ (0.09)