Financial Derivatives (Derivative Assets and Liabilitites Offsetting) (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Offsetting Derivative Assets [Abstract]
Derivative Asset, Gross Fair Value	$ 7,343	$ 3,502
Derivative Asset, Fair Value Offset Amount	864	690
Derivative Asset, Cash Collateral	1,699	616
Derivative Asset, Net	4,780	2,196
Derivative Asset, Securities Collateral Held Under Master Netting Agreements	617	215
Derivative Asset, Fair Value, Amount Offset Against Collateral	4,163	1,981
Offsetting Derivative Liabilities [Abstract]
Derivative Liability, Gross Fair Value	2,710	2,019
Derivative Liability, Fair Value Offset Amount	864	690
Derivative Liability, Cash Collateral	1,308	790
Derivative Liability, Net	538	539
Derivative Liability, Fair Value of Collateral
Derivative Liability, Fair Value, Amount Offset Against Collateral	538	539
Interest Rate Contracts [Member] \| Over the Counter Cleared [Member]
Offsetting Derivative Assets [Abstract]
Derivative Asset, Gross Fair Value	31	14
Derivative Asset, Net	31	14
Derivative Asset, Fair Value, Amount Offset Against Collateral	31	14
Offsetting Derivative Liabilities [Abstract]
Derivative Liability, Gross Fair Value	23	14
Derivative Liability, Net	23	14
Derivative Liability, Fair Value, Amount Offset Against Collateral	23	14
Interest Rate Contracts [Member] \| Over the Counter [Member]
Offsetting Derivative Assets [Abstract]
Derivative Asset, Gross Fair Value	6,534	2,969
Derivative Asset, Fair Value Offset Amount	433	365
Derivative Asset, Cash Collateral	1,673	593
Derivative Asset, Net	4,428	2,011
Derivative Asset, Securities Collateral Held Under Master Netting Agreements	616	215
Derivative Asset, Fair Value, Amount Offset Against Collateral	3,812	1,796
Offsetting Derivative Liabilities [Abstract]
Derivative Liability, Gross Fair Value	1,875	1,279
Derivative Liability, Fair Value Offset Amount	589	475
Derivative Liability, Cash Collateral	1,159	692
Derivative Liability, Net	127	112
Derivative Liability, Fair Value, Amount Offset Against Collateral	127	112
Commodity Contract [Member]
Offsetting Derivative Assets [Abstract]
Derivative Asset, Gross Fair Value	497	306
Derivative Asset, Fair Value Offset Amount	299	198
Derivative Asset, Cash Collateral	14	18
Derivative Asset, Net	184	90
Derivative Asset, Fair Value, Amount Offset Against Collateral	184	90
Offsetting Derivative Liabilities [Abstract]
Derivative Liability, Gross Fair Value	475	301
Derivative Liability, Fair Value Offset Amount	206	152
Derivative Liability, Cash Collateral	59	17
Derivative Liability, Net	210	132
Derivative Liability, Fair Value, Amount Offset Against Collateral	210	132
Foreign Exchange And Other Contract [Member]
Offsetting Derivative Assets [Abstract]
Derivative Asset, Gross Fair Value	281	213
Derivative Asset, Fair Value Offset Amount	132	127
Derivative Asset, Cash Collateral	12	5
Derivative Asset, Net	137	81
Derivative Asset, Securities Collateral Held Under Master Netting Agreements	1
Derivative Asset, Fair Value, Amount Offset Against Collateral	136	81
Offsetting Derivative Liabilities [Abstract]
Derivative Liability, Gross Fair Value	337	425
Derivative Liability, Fair Value Offset Amount	69	63
Derivative Liability, Cash Collateral	90	81
Derivative Liability, Net	178	281
Derivative Liability, Fair Value, Amount Offset Against Collateral	$ 178	$ 281

Amount of obligation to return cash collateral under master netting arrangements offset against derivative assets.

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Fair value of liability associated with financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset.

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

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Amount of right to receive securities collateral under master netting arrangements that have not been offset against derivative liabilities.

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Fair value, before effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets elected not to be offset. Excludes assets not subject to a master netting arrangement.

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Fair value of asset associated with financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset.

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