Accumulated Other Comprehensive Loss (Composition of Accumulated Other Comprehensive Income) (Details) - USD ($) $ in Millions	12 Months Ended
	Jan. 31, 2021	Jan. 31, 2020	Jan. 31, 2019
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balances	$ (12,805)	$ (11,542)	$ (10,181)
Other comprehensive income (loss) before reclassifications, net	7	(1,279)	(2,067)
Reclassifications to income, net	1,032	16	2,142
Ending balances	(11,766)	(12,805)	(11,542)
Walmart Brazil [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Reclassifications to income, net			2,000
Walmart Argentina [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Reclassifications to income, net	800
Cumulative Effect, Period of Adoption, Adjustment [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balances			(1,436)
Accumulated Currency Translation and Other Adjustments Attributable to Parent [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balances	(11,827)	(12,085)	(12,136)
Other comprehensive income (loss) before reclassifications, net	214	281	(2,093)
Reclassifications to income, net	841	(23)	2,055
Ending balances	(10,772)	(11,827)	(12,085)
Accumulated Currency Translation and Other Adjustments Attributable to Parent [Member] | Cumulative Effect, Period of Adoption, Adjustment [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balances			89
Accumulated Net Investment Gain Or Loss Attributable To Parent [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balances	1,517	1,395	1,030
Other comprehensive income (loss) before reclassifications, net	(221)	122	272
Reclassifications to income, net	0	0	0
Ending balances	1,296	1,517	1,395
Accumulated Net Investment Gain Or Loss Attributable To Parent [Member] | Cumulative Effect, Period of Adoption, Adjustment [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balances			93
AOCI, Accumulated Gain (Loss), Debt Securities, Available-for-sale, Parent [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balances	0	0	1,646
Other comprehensive income (loss) before reclassifications, net	0	0	0
Reclassifications to income, net	0	0	0
Ending balances	0	0	0
AOCI, Accumulated Gain (Loss), Debt Securities, Available-for-sale, Parent [Member] | Cumulative Effect, Period of Adoption, Adjustment [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balances			(1,646)
Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balances	(539)	(140)	122
Other comprehensive income (loss) before reclassifications, net	186	(399)	(339)
Reclassifications to income, net	49	0	49
Ending balances	(304)	(539)	(140)
Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent [Member] | Cumulative Effect, Period of Adoption, Adjustment [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balances			28
Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balances	(1,956)	(712)	(843)
Other comprehensive income (loss) before reclassifications, net	(172)	(1,283)	93
Reclassifications to income, net	142	39	38
Ending balances	$ (1,986)	$ (1,956)	(712)
Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member] | Cumulative Effect, Period of Adoption, Adjustment [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balances			$ 0