Information about Segments and Geographic Areas (Long-Lived Assets by Geographic Area) (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	$ 107,142	$ 97,116
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	81,160	74,882
International
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	$ 25,982	$ 22,234