Derivative Financial Instruments And Hedging Activities (Details) - USD ($) $ in Millions	Jun. 30, 2017	Dec. 31, 2016
Designated as Hedging Instrument [Member] \| Other Assets [Member]
Derivatives, Fair Value [Line Items]
Derivative asset, Notional amount	$ 5,821	$ 3,070
Derivative asset, Fair value	48	12
Designated as Hedging Instrument [Member] \| Other Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative liability, Notional amount	9,310	8,991
Derivative liability, Fair value	238	310
Designated as Hedging Instrument [Member] \| Fair Value Hedging [Member] \| Other Assets [Member] \| Interest Rate Swaps [Member] \| Level 2 [Member]
Derivatives, Fair Value [Line Items]
Derivative asset, Notional amount	2,500	0
Derivative asset, Fair value	21	0
Designated as Hedging Instrument [Member] \| Fair Value Hedging [Member] \| Other Liabilities [Member] \| Interest Rate Swaps [Member] \| Level 2 [Member]
Derivatives, Fair Value [Line Items]
Derivative liability, Notional amount	8,854	7,700
Derivative liability, Fair value	238	276
Designated as Hedging Instrument [Member] \| Cash Flow Hedging [Member] \| Other Assets [Member] \| Interest Rate Swaps [Member] \| Level 2,3 [Member]
Derivatives, Fair Value [Line Items]
Derivative asset, Notional amount	2,466	3,070
Derivative asset, Fair value	12	12
Designated as Hedging Instrument [Member] \| Cash Flow Hedging [Member] \| Other Assets [Member] \| Foreign Currency Swaps [Member] \| Level 2 [Member]
Derivatives, Fair Value [Line Items]
Derivative asset, Notional amount	855	0
Derivative asset, Fair value	15	0
Designated as Hedging Instrument [Member] \| Cash Flow Hedging [Member] \| Other Liabilities [Member] \| Interest Rate Swaps [Member] \| Level 2,3 [Member]
Derivatives, Fair Value [Line Items]
Derivative liability, Notional amount	456	500
Derivative liability, Fair value	0	1
Designated as Hedging Instrument [Member] \| Cash Flow Hedging [Member] \| Other Liabilities [Member] \| Foreign Currency Swaps [Member] \| Level 2 [Member]
Derivatives, Fair Value [Line Items]
Derivative liability, Notional amount	0	791
Derivative liability, Fair value	0	33
Not Designated as Hedging Instrument [Member] \| Other Assets [Member]
Derivatives, Fair Value [Line Items]
Derivative asset, Notional amount	41,369	17,657
Derivative asset, Fair value	195	80
Not Designated as Hedging Instrument [Member] \| Other Assets [Member] \| Interest Rate Swaps [Member] \| Level 2,3 [Member]
Derivatives, Fair Value [Line Items]
Derivative asset, Notional amount	24,881	7,959
Derivative asset, Fair value	117	54
Not Designated as Hedging Instrument [Member] \| Other Assets [Member] \| Foreign Currency Swaps [Member] \| Level 2 [Member]
Derivatives, Fair Value [Line Items]
Derivative asset, Notional amount	1,141	0
Derivative asset, Fair value	42	0
Not Designated as Hedging Instrument [Member] \| Other Assets [Member] \| Interest Rate Options [Member] \| Level 2 [Member]
Derivatives, Fair Value [Line Items]
Derivative asset, Notional amount	15,347	9,698
Derivative asset, Fair value	36	26
Not Designated as Hedging Instrument [Member] \| Other Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative liability, Notional amount	35,791	18,316
Derivative liability, Fair value	97	54
Not Designated as Hedging Instrument [Member] \| Other Liabilities [Member] \| Interest Rate Swaps [Member] \| Level 2,3 [Member]
Derivatives, Fair Value [Line Items]
Derivative liability, Notional amount	17,746	6,170
Derivative liability, Fair value	61	28
Not Designated as Hedging Instrument [Member] \| Other Liabilities [Member] \| Foreign Currency Swaps [Member] \| Level 2 [Member]
Derivatives, Fair Value [Line Items]
Derivative liability, Notional amount	331	0
Derivative liability, Fair value	0	0
Not Designated as Hedging Instrument [Member] \| Other Liabilities [Member] \| Interest Rate Options [Member] \| Level 2 [Member]
Derivatives, Fair Value [Line Items]
Derivative liability, Notional amount	17,714	12,146
Derivative liability, Fair value	$ 36	$ 26

Nominal or face amount used to calculate payments on the derivative asset.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1A
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5579245-113959

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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+ References

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+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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- Definition

Nominal or face amount used to calculate payments on the derivative liability.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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+ References

No definition available.

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