Hedging Activities (Summary of Notional Amounts and Respective Fair Values of Derivative Financial Instruments) (Details) - USD ($) $ in Millions		Mar. 31, 2018	Dec. 31, 2017
Notional amount		$ 16,574	$ 15,718
Asset derivatives, fair value		197	265
Liability derivatives, fair value		(952)	(374)
Foreign Exchange Contract [Member] | Other Assets [Member]
Asset derivatives, fair value		3	1
Foreign Exchange Contract [Member] | Designated as Hedging Instrument [Member]
Notional amount	[1]	313	294
Foreign Exchange Contract [Member] | Designated as Hedging Instrument [Member] | Other Current Assets [Member]
Asset derivatives, fair value	[1]	16	20
Foreign Exchange Contract [Member] | Not Designated as Hedging Instrument [Member]
Notional amount		1,431	599
Foreign Exchange Contract [Member] | Not Designated as Hedging Instrument [Member] | Other Current Assets [Member]
Asset derivatives, fair value		3	2
Foreign Exchange Contract [Member] | Not Designated as Hedging Instrument [Member] | Other Accrued Liabilities [Member]
Liability derivatives, fair value		(14)	(7)
Interest Rate Swap [Member] | Designated as Hedging Instrument [Member]
Notional amount		550	550
Interest Rate Swap [Member] | Designated as Hedging Instrument [Member] | Other Liabilities [Member]
Liability derivatives, fair value		(11)	(8)
Translated Earnings Contracts [Member] | Other Assets [Member]
Asset derivatives, fair value		69	66
Translated Earnings Contracts [Member] | Other Liabilities [Member]
Liability derivatives, fair value		(819)	(325)
Translated Earnings Contracts [Member] | Not Designated as Hedging Instrument [Member]
Notional amount		14,280	14,275
Translated Earnings Contracts [Member] | Not Designated as Hedging Instrument [Member] | Other Current Assets [Member]
Asset derivatives, fair value		106	176
Translated Earnings Contracts [Member] | Not Designated as Hedging Instrument [Member] | Other Accrued Liabilities [Member]
Liability derivatives, fair value		$ (108)	$ (34)

[1] Cash flow hedges with a typical duration of 24 months or less.