Supplemental Financial Statement Information (Property and Equipment) (Details) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Property, Plant and Equipment, Net [Abstract]
Property and equipment, gross	$ 137,075	$ 126,462
Less: accumulated depreciation	(45,378)	(41,713)
Property and equipment, net	91,697	84,749
Land and buildings
Property, Plant and Equipment, Net [Abstract]
Property and equipment, gross	55,910	49,732
Information technology assets
Property, Plant and Equipment, Net [Abstract]
Property and equipment, gross	51,188	45,906
Construction in progress
Property, Plant and Equipment, Net [Abstract]
Property and equipment, gross	21,825	23,111
Leasehold improvements
Property, Plant and Equipment, Net [Abstract]
Property and equipment, gross	7,951	7,516
Furniture and fixtures
Property, Plant and Equipment, Net [Abstract]
Property and equipment, gross	$ 201	$ 197