Summary of Significant Accounting Policies (Schedule of Property, Plant and Equipment) (Details) - USD ($) $ in Millions	12 Months Ended
	Jan. 31, 2021	Jan. 31, 2020
Property, Plant and Equipment [Line Items]
Property and equipment	$ 180,571	$ 195,028
Accumulated depreciation	(88,370)	(89,820)
Property and equipment, net	92,201	105,208
Land [Member]
Property, Plant and Equipment [Line Items]
Property and equipment	19,308	24,619
Building and Building Improvements [Member]
Property, Plant and Equipment [Line Items]
Property and equipment	$ 97,582	105,674
Building and Building Improvements [Member] | Minimum
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	3 years
Building and Building Improvements [Member] | Maximum
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	40 years
Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Property and equipment	$ 56,639	58,607
Furniture and Fixtures [Member] | Minimum
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	1 year
Furniture and Fixtures [Member] | Maximum
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	30 years
Transportation Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment	$ 2,301	2,377
Transportation Equipment [Member] | Minimum
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	3 years
Transportation Equipment [Member] | Maximum
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	15 years
Construction in Progress [Member]
Property, Plant and Equipment [Line Items]
Property and equipment	$ 4,741	$ 3,751