Property and Equipment - Components (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Gross property and equipment	$ 95,770	$ 72,656
Total accumulated depreciation	33,973	23,790
Total property and equipment, net	61,797	48,866	$ 29,114
Land and buildings
Property, Plant and Equipment [Line Items]
Gross property and equipment	31,741	23,896
Equipment
Property, Plant and Equipment [Line Items]
Gross property and equipment	54,591	42,244
Other assets
Property, Plant and Equipment [Line Items]
Gross property and equipment	2,577	2,438
Construction in progress
Property, Plant and Equipment [Line Items]
Gross property and equipment	$ 6,861	$ 4,078