Information about Segments and Geographic Areas (Revenues by Geographic Area) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	$ 90,272	$ 74,989	$ 66,001
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	42,781	34,810	29,482
United Kingdom
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	7,787	7,067	6,483
Rest of the world
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	$ 39,704	$ 33,112	$ 30,036