Derivative Financial Instruments and Hedging Activities (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
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	$ 10,510	$ 11,110
Derivative asset, Fair value	5	2
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, Fair value	510	290
Designated as Hedging Instrument [Member] \| Cash Flow Hedging [Member] \| Other Assets [Member] \| Interest Rate Swaps [Member]
Derivatives, Fair Value [Line Items]
Derivative asset, Notional amount	905	2,177
Derivative asset, Fair value	10	15
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	2,108	1,574
Derivative asset, Fair value	71	103
Designated as Hedging Instrument [Member] \| Cash Flow Hedging [Member] \| Other Liabilities [Member] \| Interest Rate Swaps [Member]
Derivatives, Fair Value [Line Items]
Derivative liability, Fair value	0	0
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, Fair value	27	0
Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Fair value of assets (liabilities) available for offset	459	284
Not Designated as Hedging Instrument [Member] \| Other Assets [Member]
Derivatives, Fair Value [Line Items]
Derivative asset, Notional amount	108,543	98,000
Derivative asset, Fair value	695	553
Collateral available for netting	718	299
Not Designated as Hedging Instrument [Member] \| Other Assets [Member] \| Interest Rate Swaps [Member]
Derivatives, Fair Value [Line Items]
Derivative asset, Notional amount	93,162	81,938
Derivative asset, Fair value	551	329
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	1,858	1,201
Derivative asset, Fair value	58	104
Not Designated as Hedging Instrument [Member] \| Other Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative liability, Fair value	1,255	497
Cash held	55	25
Not Designated as Hedging Instrument [Member] \| Other Liabilities [Member] \| Interest Rate Swaps [Member]
Derivatives, Fair Value [Line Items]
Derivative liability, Fair value	670	207
Not Designated as Hedging Instrument [Member] \| Other Liabilities [Member] \| Foreign Currency Swaps [Member] \| Level 2 [Member]
Derivatives, Fair Value [Line Items]
Derivative liability, Fair value	$ 48	$ 0

Derivative Assets (Liabilities), Net, Fair Value, Amount Not Offset Against Collateral

No definition available.

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- Definition

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

+ References

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-Publisher FASB
-Name Accounting Standards Codification
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- Definition

Amount of obligation to return cash collateral under master netting arrangements that have not been offset against derivative assets.

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- Definition

Amount of right to receive cash collateral under master netting arrangements offset against derivative liabilities.

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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