Revenues (Revenue by Geographic Location) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	$ 27,772	$ 22,451	$ 78,532	$ 64,208
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	12,930	10,649	37,021	30,065
EMEA
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	9,097	7,392	25,733	22,007
APAC
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	4,199	3,248	11,548	8,951
Other Americas
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	$ 1,546	$ 1,162	$ 4,230	$ 3,185