Operating Income by Segment, Interest, Net, and Unrealized (Gains) and Losses (Details) - USD ($) $ in Millions |
3 Months Ended | |
|---|---|---|
Apr. 30, 2019 |
Apr. 30, 2018 |
|
| Segment Reporting Information [Line Items] | ||
| Operating income | $ 4,945 | $ 5,154 |
| Interest, net | 625 | 487 |
| Other (gains) and losses | (837) | 1,845 |
| Income before income taxes | 5,157 | 2,822 |
| Walmart U.S. | ||
| Segment Reporting Information [Line Items] | ||
| Operating income | 4,142 | 3,927 |
| Walmart International | ||
| Segment Reporting Information [Line Items] | ||
| Operating income | 738 | 1,265 |
| Sam's Club | ||
| Segment Reporting Information [Line Items] | ||
| Operating income | 451 | 325 |
| Corporate and support | ||
| Segment Reporting Information [Line Items] | ||
| Operating income | $ (386) | $ (363) |