Financial Instruments (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Derivative [Line Items]
Other comprehensive income (loss), foreign currency transaction and translation gain (loss) arising during period, net of tax	$ (14)	$ (2,248)	$ (1,746)
Cash Flow Hedging [Member]
Derivative [Line Items]
Foreign currency maturity	May 31, 2024
Foreign Exchange Contract [Member]
Derivative [Line Items]
Foreign exchange contracts, notional amounts	$ 29,200	24,900
Derivative gains to be reclassified to earnings	60
Foreign Exchange Contract [Member] | Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Foreign exchange contracts, notional amounts	13,600	15,300
Gains/(losses) from foreign currency contracts not designated as hedging instruments	(85)	(587)	(481)
Foreign Exchange Contract [Member] | Cash Flow Hedging [Member]
Derivative [Line Items]
Foreign exchange contracts, notional amounts	$ 5,000	3,200
Foreign Exchange Contract [Member] | Cash Flow Hedging [Member] | Maximum [Member]
Derivative [Line Items]
Maturity period	18 months
Foreign Exchange Contract [Member] | Net Investment Hedging [Member]
Derivative [Line Items]
Foreign exchange contracts, notional amounts	$ 10,600	6,400
Other comprehensive income (loss), foreign currency transaction and translation gain (loss) arising during period, net of tax	$ 430	$ 761	$ 952