Financial Derivatives (Derivative Assets and Liabilitites Offsetting) (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Offsetting Derivative Assets [Abstract]
Derivative Asset, Gross Fair Value	$ 8,179	$ 3,502
Derivative Asset, Fair Value Offset Amount	1,196	690
Derivative Asset, Cash Collateral	1,825	616
Derivative Asset, Net	5,158	2,196
Derivative Asset, Securities Collateral Held Under Master Netting Agreements	675	215
Derivative Asset, Fair Value, Amount Offset Against Collateral	4,483	1,981
Offsetting Derivative Liabilities [Abstract]
Derivative Liability, Gross Fair Value	3,229	2,019
Derivative Liability, Fair Value Offset Amount	1,196	690
Derivative Liability, Cash Collateral	1,229	790
Derivative Liability, Net	804	539
Derivative Liability, Fair Value of Collateral
Derivative Liability, Fair Value, Amount Offset Against Collateral	804	539
Interest Rate Contracts [Member] | Over the Counter Cleared [Member]
Offsetting Derivative Assets [Abstract]
Derivative Asset, Gross Fair Value	66	14
Derivative Asset, Net	66	14
Derivative Asset, Fair Value, Amount Offset Against Collateral	66	14
Offsetting Derivative Liabilities [Abstract]
Derivative Liability, Gross Fair Value	48	14
Derivative Liability, Net	48	14
Derivative Liability, Fair Value, Amount Offset Against Collateral	48	14
Interest Rate Contracts [Member] | Over the Counter [Member]
Offsetting Derivative Assets [Abstract]
Derivative Asset, Gross Fair Value	7,046	2,969
Derivative Asset, Fair Value Offset Amount	515	365
Derivative Asset, Cash Collateral	1,757	593
Derivative Asset, Net	4,774	2,011
Derivative Asset, Securities Collateral Held Under Master Netting Agreements	674	215
Derivative Asset, Fair Value, Amount Offset Against Collateral	4,100	1,796
Offsetting Derivative Liabilities [Abstract]
Derivative Liability, Gross Fair Value	2,070	1,279
Derivative Liability, Fair Value Offset Amount	815	475
Derivative Liability, Cash Collateral	1,111	692
Derivative Liability, Net	144	112
Derivative Liability, Fair Value, Amount Offset Against Collateral	144	112
Commodity Contract [Member]
Offsetting Derivative Assets [Abstract]
Derivative Asset, Gross Fair Value	657	306
Derivative Asset, Fair Value Offset Amount	443	198
Derivative Asset, Cash Collateral	61	18
Derivative Asset, Net	153	90
Derivative Asset, Fair Value, Amount Offset Against Collateral	153	90
Offsetting Derivative Liabilities [Abstract]
Derivative Liability, Gross Fair Value	635	301
Derivative Liability, Fair Value Offset Amount	267	152
Derivative Liability, Cash Collateral	25	17
Derivative Liability, Net	343	132
Derivative Liability, Fair Value, Amount Offset Against Collateral	343	132
Foreign Exchange And Other Contract [Member]
Offsetting Derivative Assets [Abstract]
Derivative Asset, Gross Fair Value	410	213
Derivative Asset, Fair Value Offset Amount	238	127
Derivative Asset, Cash Collateral	7	5
Derivative Asset, Net	165	81
Derivative Asset, Securities Collateral Held Under Master Netting Agreements	1
Derivative Asset, Fair Value, Amount Offset Against Collateral	164	81
Offsetting Derivative Liabilities [Abstract]
Derivative Liability, Gross Fair Value	476	425
Derivative Liability, Fair Value Offset Amount	114	63
Derivative Liability, Cash Collateral	93	81
Derivative Liability, Net	269	281
Derivative Liability, Fair Value, Amount Offset Against Collateral	$ 269	$ 281