Financial Derivatives (Total Derivatives) (Details) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Derivative [Line Items]
Derivative, notional amount	$ 513,110	$ 466,707
Derivative asset, fair value	6,447	6,533
Derivative liability, fair value	3,719	2,756
Derivative asset, fair value offset amount	919	720
Derivative liability, fair value offset amount	919	720
Derivative asset, cash collateral	859	1,434
Derivative liability, cash collateral	2,078	1,452
Derivative asset, net fair value	4,669	4,379
Derivative liability, net fair value	722	584
Commodity contracts:
Derivative [Line Items]
Derivative asset, fair value	1,469	411
Derivative liability, fair value	1,485	384
Derivative asset, cash collateral	15	4
Derivative liability, cash collateral	997	103
Foreign exchange contracts and other
Derivative [Line Items]
Derivative asset, fair value	254	271
Derivative liability, fair value	457	590
Derivative asset, cash collateral	14	4
Derivative liability, cash collateral	132	170
Designated as Hedging Instruments under GAAP
Derivative [Line Items]
Derivative, notional amount	61,798	48,103
Derivative asset, fair value	20	14
Derivative liability, fair value	46	22
Designated as Hedging Instruments under GAAP \| Fair value hedges \| Interest Rate Contracts
Derivative [Line Items]
Derivative, notional amount	25,293	24,153
Designated as Hedging Instruments under GAAP \| Cash flow hedges \| Interest Rate Contracts
Derivative [Line Items]
Derivative, notional amount	35,405	22,875
Derivative asset, fair value	20	14
Derivative liability, fair value	13
Designated as Hedging Instruments under GAAP \| Net investment hedges \| Foreign exchange contracts:
Derivative [Line Items]
Derivative, notional amount	1,100	1,075
Derivative asset, fair value
Derivative liability, fair value	33	22
Not Designated as Hedging Instrument under GAAP
Derivative [Line Items]
Derivative, notional amount	451,312	418,604
Derivative asset, fair value	6,427	6,519
Derivative liability, fair value	3,673	2,734
Not Designated as Hedging Instrument under GAAP \| Mortgage Banking \| Interest Rate Contracts
Derivative [Line Items]
Derivative, notional amount	61,340	66,471
Derivative asset, fair value	151	158
Derivative liability, fair value	83	79
Not Designated as Hedging Instrument under GAAP \| Mortgage Banking \| Swaps \| Interest Rate Contracts
Derivative [Line Items]
Derivative, notional amount	32,917	50,511
Derivative asset, fair value
Derivative liability, fair value	1
Not Designated as Hedging Instrument under GAAP \| Mortgage Banking \| Futures \| Interest Rate Contracts
Derivative [Line Items]
Derivative, notional amount	3,930	2,841
Not Designated as Hedging Instrument under GAAP \| Mortgage Banking \| Mortgage-backed commitments \| Interest Rate Contracts
Derivative [Line Items]
Derivative, notional amount	11,609	11,288
Derivative asset, fair value	104	147
Derivative liability, fair value	58	77
Not Designated as Hedging Instrument under GAAP \| Mortgage Banking \| Other \| Interest Rate Contracts
Derivative [Line Items]
Derivative, notional amount	12,884	1,831
Derivative asset, fair value	47	11
Derivative liability, fair value	24	2
Not Designated as Hedging Instrument under GAAP \| Customer Contracts
Derivative [Line Items]
Derivative, notional amount	376,333	341,202
Derivative asset, fair value	6,220	6,357
Derivative liability, fair value	3,360	2,330
Not Designated as Hedging Instrument under GAAP \| Customer Contracts \| Interest Rate Contracts
Derivative [Line Items]
Derivative, notional amount	336,995	305,663
Derivative asset, fair value	4,553	5,679
Derivative liability, fair value	1,681	1,703
Not Designated as Hedging Instrument under GAAP \| Customer Contracts \| Commodity contracts:
Derivative [Line Items]
Derivative, notional amount	11,970	8,919
Derivative asset, fair value	1,469	411
Derivative liability, fair value	1,485	384
Not Designated as Hedging Instrument under GAAP \| Customer Contracts \| Foreign exchange contracts and other
Derivative [Line Items]
Derivative, notional amount	27,368	26,620
Derivative asset, fair value	198	267
Derivative liability, fair value	194	243
Not Designated as Hedging Instrument under GAAP \| Customer Contracts \| Swaps \| Interest Rate Contracts
Derivative [Line Items]
Derivative, notional amount	309,609	280,125
Derivative asset, fair value	4,395	5,475
Derivative liability, fair value	1,570	1,601
Not Designated as Hedging Instrument under GAAP \| Customer Contracts \| Swaps \| Commodity contracts:
Derivative [Line Items]
Derivative, notional amount	8,535	6,149
Derivative asset, fair value	1,207	350
Derivative liability, fair value	1,223	323
Not Designated as Hedging Instrument under GAAP \| Customer Contracts \| Futures \| Interest Rate Contracts
Derivative [Line Items]
Derivative, notional amount	981	1,235
Not Designated as Hedging Instrument under GAAP \| Customer Contracts \| Mortgage-backed commitments \| Interest Rate Contracts
Derivative [Line Items]
Derivative, notional amount	4,236	4,178
Derivative asset, fair value	10	11
Derivative liability, fair value	8	14
Not Designated as Hedging Instrument under GAAP \| Customer Contracts \| Other \| Interest Rate Contracts
Derivative [Line Items]
Derivative, notional amount	22,169	20,125
Derivative asset, fair value	148	193
Derivative liability, fair value	103	88
Not Designated as Hedging Instrument under GAAP \| Customer Contracts \| Other \| Commodity contracts:
Derivative [Line Items]
Derivative, notional amount	3,435	2,770
Derivative asset, fair value	262	61
Derivative liability, fair value	262	61
Not Designated as Hedging Instrument under GAAP \| Other Risk Management Activity \| Foreign exchange contracts and other
Derivative [Line Items]
Derivative, notional amount	13,639	10,931
Derivative asset, fair value	56	4
Derivative liability, fair value	$ 230	$ 325

Fair value of the gross assets less the offsetting amount of derivative assets.

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