Derivative Financial Instruments And Hedging Activities - Derivatives Income (Losses) Recognized in Income (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Derivatives, Fair Value [Line Items]
Total	$ 46	$ 15	$ 216	$ 27
Increase (decrease) in fair value of interest rate contracts	57		19
Increase (decrease) in fair value of hedged debt	54		14
Cash Flow Hedging [Member]
Derivatives, Fair Value [Line Items]
Gains Recognized In Accumulated Other Comprehensive Loss	2	0	(2)	0
Gains Reclassified From Accumulated Other Comprehensive Loss Into Income	(3)	0	(3)	0
Cash Flow Hedging [Member] \| Interest Rate Contract [Member]
Derivatives, Fair Value [Line Items]
Gains Recognized In Accumulated Other Comprehensive Loss	2	0	(2)	0
Gains Reclassified From Accumulated Other Comprehensive Loss Into Income	1	0	1	0
Cash Flow Hedging [Member] \| Foreign Currency Contracts [Member]
Derivatives, Fair Value [Line Items]
Gains Recognized In Accumulated Other Comprehensive Loss	0	0	0	0
Gains Reclassified From Accumulated Other Comprehensive Loss Into Income	(4)	0	(4)	0
Designated as Hedging Instrument [Member] \| Fair Value Hedging [Member] \| Interest Rate Contract [Member]
Derivatives, Fair Value [Line Items]
Interest rate contracts	6	0	26	0
Designated as Hedging Instrument [Member] \| Cash Flow Hedging [Member] \| Interest Rate Contract [Member]
Derivatives, Fair Value [Line Items]
Interest rate contracts	(2)	0	(2)	0
Designated as Hedging Instrument [Member] \| Cash Flow Hedging [Member] \| Foreign Currency Contracts [Member]
Derivatives, Fair Value [Line Items]
Interest rate contracts	(1)	0	(1)	0
Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Interest rate contracts	7	(13)	(8)	(12)
Foreign currency derivatives	$ 36	$ 28	$ 201	$ 39

Amount of the increase (decrease) in fair value of the hedged item in a fair value hedge 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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- Definition

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
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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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- Definition

Amount of realized and unrealized gain (loss) of derivative instruments not designated or qualifying as hedging instruments.

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Amount of gain (loss) recognized in earnings in the period from the increase (decrease) in fair value of foreign currency derivatives not designated 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 (e)
-URI http://asc.fasb.org/extlink&oid=64837297&loc=SL5624171-113959

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Amount of gain (loss) included in earnings for the period from the increase (decrease) in fair value of interest rate derivatives not designated 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 4A
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=64837297&loc=SL5618551-113959

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-Publisher FASB
-Name Accounting Standards Codification
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Amount of unrealized gain (loss) included in earnings related to the fair value of the hedged item in an interest rate fair value hedge, offset by the gain (loss) on the hedging instrument to the extent that the fair value hedge is determined to be effective.

+ 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 (a)
-URI http://asc.fasb.org/extlink&oid=64837297&loc=SL5624171-113959

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Amount of unrealized gain (loss) related to the fair value of interest rate derivatives designated as fair value hedging instruments, as offset by the gain (loss) on the hedged item to the extent that the fair value hedge is determined to be effective.

+ 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

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-Publisher FASB
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-URI http://asc.fasb.org/extlink&oid=64837297&loc=SL5624171-113959

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