Hedging Activities (Effect on Consolidated Financial Statements) (Details) - Not Designated as Hedging Instrument [Member] - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2018	Mar. 31, 2017
Gain (loss) recognized in income	$ (641)	$ (436)
Foreign Exchange Contracts, Balance Sheet [Member] \| Foreign Currency Transaction and Hedge Gain (Loss), Net [Member]
Gain (loss) recognized in income	(19)	2
Translated Earnings Contracts [Member] \| Foreign Currency Transaction and Hedge Gain (Loss), Net [Member]
Gain (loss) recognized in income	$ (622)	$ (438)

Amount of increase (decrease) in the fair value of derivatives recognized in the income statement.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4A
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5618551-113959

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4C
-Subparagraph (a),(c),(d),(e)
-URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5624171-113959

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration