Hedging Activities (Summary of Notional Amounts and Respective Fair Values of Derivative Financial Instruments) (Details) - USD ($) $ in Millions	Jun. 30, 2017	Dec. 31, 2016
Notional amount	$ 15,935	$ 18,609
Asset derivatives, fair value	277	581
Liability derivatives, fair value	(401)	(370)
Foreign Exchange Contract [Member] | Other Assets [Member]
Asset derivatives, fair value	10
Foreign Exchange Contract [Member] | Designated as Hedging Instrument [Member]
Notional amount	472	458
Foreign Exchange Contract [Member] | Designated as Hedging Instrument [Member] | Other Current Assets [Member]
Asset derivatives, fair value	10	1
Foreign Exchange Contract [Member] | Designated as Hedging Instrument [Member] | Other Accrued Liabilities [Member]
Liability derivatives, fair value	(7)	(29)
Foreign Exchange Contract [Member] | Not Designated as Hedging Instrument [Member]
Notional amount	649	890
Foreign Exchange Contract [Member] | Not Designated as Hedging Instrument [Member] | Other Current Assets [Member]
Asset derivatives, fair value	4	11
Foreign Exchange Contract [Member] | Not Designated as Hedging Instrument [Member] | Other Accrued Liabilities [Member]
Liability derivatives, fair value	(7)	(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	(5)	(5)
Translated Earnings Contracts [Member] | Other Assets [Member]
Asset derivatives, fair value	40	146
Translated Earnings Contracts [Member] | Other Liabilities [Member]
Liability derivatives, fair value	(353)	(277)
Translated Earnings Contracts [Member] | Not Designated as Hedging Instrument [Member]
Notional amount	14,264	16,711
Translated Earnings Contracts [Member] | Not Designated as Hedging Instrument [Member] | Other Current Assets [Member]
Asset derivatives, fair value	213	423
Translated Earnings Contracts [Member] | Not Designated as Hedging Instrument [Member] | Other Accrued Liabilities [Member]
Liability derivatives, fair value	$ (29)	$ (52)