Segments (Segment Reporting Information) (Details) - USD ($) $ in Millions Jan. 31, 2018 Jan. 31, 2017 Jan. 31, Jan. 31, 2016 Jan. 31, 2014 2015 Walmart in total Net sales $ 495,761 $ 481,317 $ 478,614 $ 482,229 $ 473,076 Operating income (loss) 20,437 22,764 24,105 27,147 26,872 Interest, net (2,178) (2,267) (2,467) (2,348) (2,216) Gain (loss) on extinguishment of debt (3,136) Income before income taxes 15,123 20,497 21,638 24,799 24,656 Total assets 204,522 198,825 199,581 203,706 204,751 Depreciation and amortization 10,529 10,080 9,454 9,173 8,870 Capital expenditures 10,051 10,619 11,477 12,174 13,115 Walmart U.S. Net sales 318,477 307,833 298,378 288,049 279,406 Operating income (loss) 17,869 17,745 19,087 21,336 21,787 Total assets 104,347 104,262 103,109 101,381 98,745 Depreciation and amortization 3,655 3,298 2,800 2,665 2,640 Capital expenditures 5,680 6,090 6,728 6,286 6,378 Walmart International Net sales 118,068 116,119 123,408 136,160 136,513 Operating income (loss) 5,352 5,758 5,346 6,171 5,153 Total assets 81,549 74,508 73,720 80,505 85,370 Depreciation and amortization 2,601 2,629 2,549 2,665 2,658 Capital expenditures 2,607 2,697 2,930 3,936 4,463 Sam's Club Net sales 59,216 57,365 56,828 58,020 57,157 Operating income (loss) 982 1,671 1,820 1,976 1,843 Total assets 13,418 14,125 13,998 13,995 14,053 Depreciation and amortization 466 487 472 473 437 Capital expenditures 626 639 695 753 1,071 Corporate and support Net sales Operating income (loss) (3,766) (2,410) (2,148) (2,336) (1,911) Total assets 5,208 5,930 8,754 7,825 6,583 Depreciation and amortization 3,807 3,666 3,633 3,370 3,135 Capital expenditures 1,138 1,193 1,124 1,199 1,203