Income Effect of Derivative Financial Instruments (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Derivative [Line Items]
Gain/(Loss) Recognized in Income	$ 43	$ 477	$ 134	$ 1,109
Designated as Hedging Instrument [Member]
Derivative [Line Items]
Change in Unrealized Gain (Loss) on Fair Value Hedging Instruments	(40)	(228)	(95)	655
Change in Unrealized Gain (Loss) on Hedged Item in Fair Value Hedge	40	227	95	(634)
Designated as Hedging Instrument [Member] \| Cash Flow Hedging [Member] \| Foreign currency exchange contracts [Member]
Derivative [Line Items]
Gain/(Loss) Reclassified from AOCI to Income	115	202	357	335
Gain/(Loss) Recorded in OCI	(116)	340	90	887
Designated as Hedging Instrument [Member] \| Fair Value Hedging [Member] \| Interest rate contracts [Member]
Derivative [Line Items]
Net interest settlements and accruals excluded from the assessment of hedge effectiveness	50	95	182	292
Ineffectiveness - gain (loss) on interest rate fair value hedge		(1)	0	21
Not Designated as Hedging Instrument [Member] \| Foreign currency exchange contracts [Member]
Derivative [Line Items]
Gain/(Loss) Recognized in Income	(168)	29	(594)	61
Not Designated as Hedging Instrument [Member] \| Cross-currency interest rate swap contracts [Member]
Derivative [Line Items]
Gain/(Loss) Recognized in Income	5	128	79	463
Not Designated as Hedging Instrument [Member] \| Interest rate contracts [Member]
Derivative [Line Items]
Gain/(Loss) Recognized in Income	20	21	57	(70)
Not Designated as Hedging Instrument [Member] \| Commodity Contract [Member]
Derivative [Line Items]
Gain/(Loss) Recognized in Income	$ 21	$ 3	$ 53	$ 7

Amount of gain (loss) from the increase (decrease) in fair value of derivative and nonderivative instruments designated as fair value hedging instruments recognized in the income statement.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 25
-Section 50
-Paragraph 1
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=6886632&loc=d3e76258-113986

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Amount of the increase (decrease) in fair value of the hedged item in a fair value hedge recognized in the income statement.

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

+ References

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=64837297&loc=SL5618551-113959

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-Paragraph 4C
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The effective portion of net gain (loss) reclassified from accumulated other comprehensive income into income on derivative instruments designated and qualifying as hedging instruments.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4C
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=64837297&loc=SL5624171-113959

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4D
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=64837297&loc=SL5624177-113959

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The effective portion of gains and losses (net) on derivative instruments designated and qualifying as hedging instruments that was recognized in other comprehensive income during the current period.

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The net gain (loss) included in earnings for the period relating to components of the gain (loss) on interest rate fair value hedging instruments excluded from the assessment of fair value hedge effectiveness.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 25
-Section 50
-Paragraph 1
-Subparagraph (a)(2)
-URI http://asc.fasb.org/extlink&oid=6886632&loc=d3e76258-113986

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The net gain (loss) recognized in earnings during the period due to the ineffectiveness on interest rate fair value hedges.

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