Financial Derivatives (Total Derivatives) (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Derivative [Line Items]
Derivative, notional amount	$ 464,552	$ 466,707
Derivative asset, fair value	4,916	6,533
Derivative liability, fair value	3,023	2,756
Derivative asset, fair value offset amount	904	720
Derivative liability, fair value offset amount	904	720
Derivative asset, cash collateral	716	1,434
Derivative liability, cash collateral	1,295	1,452
Derivative asset, net fair value	3,296	4,379
Derivative liability, net fair value	824	584
Commodity contracts:
Derivative [Line Items]
Derivative asset, fair value	678	411
Derivative liability, fair value	653	384
Derivative asset, cash collateral	8	4
Derivative liability, cash collateral	407	103
Foreign exchange contracts and other
Derivative [Line Items]
Derivative asset, fair value	215	271
Derivative liability, fair value	442	590
Derivative asset, cash collateral	8	4
Derivative liability, cash collateral	96	170
Designated as Hedging Instruments under GAAP
Derivative [Line Items]
Derivative, notional amount	58,900	48,103
Derivative asset, fair value	14	14
Derivative liability, fair value	129	22
Designated as Hedging Instruments under GAAP \| Fair value hedges \| Interest Rate Contracts
Derivative [Line Items]
Derivative, notional amount	22,802	24,153
Designated as Hedging Instruments under GAAP \| Cash flow hedges \| Interest Rate Contracts
Derivative [Line Items]
Derivative, notional amount	35,017	22,875
Derivative asset, fair value	14	14
Derivative liability, fair value	99
Designated as Hedging Instruments under GAAP \| Net investment hedges \| Foreign exchange contracts:
Derivative [Line Items]
Derivative, notional amount	1,081	1,075
Derivative asset, fair value
Derivative liability, fair value	30	22
Not Designated as Hedging Instrument under GAAP
Derivative [Line Items]
Derivative, notional amount	405,652	418,604
Derivative asset, fair value	4,902	6,519
Derivative liability, fair value	2,894	2,734
Not Designated as Hedging Instrument under GAAP \| Mortgage Banking \| Interest Rate Contracts
Derivative [Line Items]
Derivative, notional amount	49,143	66,471
Derivative asset, fair value	202	158
Derivative liability, fair value	98	79
Not Designated as Hedging Instrument under GAAP \| Mortgage Banking \| Swaps \| Interest Rate Contracts
Derivative [Line Items]
Derivative, notional amount	26,974	50,511
Derivative asset, fair value
Not Designated as Hedging Instrument under GAAP \| Mortgage Banking \| Futures \| Interest Rate Contracts
Derivative [Line Items]
Derivative, notional amount	2,883	2,841
Not Designated as Hedging Instrument under GAAP \| Mortgage Banking \| Mortgage-backed commitments \| Interest Rate Contracts
Derivative [Line Items]
Derivative, notional amount	14,979	11,288
Derivative asset, fair value	144	147
Derivative liability, fair value	82	77
Not Designated as Hedging Instrument under GAAP \| Mortgage Banking \| Other \| Interest Rate Contracts
Derivative [Line Items]
Derivative, notional amount	4,307	1,831
Derivative asset, fair value	58	11
Derivative liability, fair value	16	2
Not Designated as Hedging Instrument under GAAP \| Customer Contracts
Derivative [Line Items]
Derivative, notional amount	345,673	341,202
Derivative asset, fair value	4,671	6,357
Derivative liability, fair value	2,556	2,330
Not Designated as Hedging Instrument under GAAP \| Customer Contracts \| Interest Rate Contracts
Derivative [Line Items]
Derivative, notional amount	309,211	305,663
Derivative asset, fair value	3,807	5,679
Derivative liability, fair value	1,731	1,703
Not Designated as Hedging Instrument under GAAP \| Customer Contracts \| Commodity contracts:
Derivative [Line Items]
Derivative, notional amount	10,279	8,919
Derivative asset, fair value	678	411
Derivative liability, fair value	653	384
Not Designated as Hedging Instrument under GAAP \| Customer Contracts \| Foreign exchange contracts and other
Derivative [Line Items]
Derivative, notional amount	26,183	26,620
Derivative asset, fair value	186	267
Derivative liability, fair value	172	243
Not Designated as Hedging Instrument under GAAP \| Customer Contracts \| Swaps \| Interest Rate Contracts
Derivative [Line Items]
Derivative, notional amount	278,447	280,125
Derivative asset, fair value	3,614	5,475
Derivative liability, fair value	1,578	1,601
Not Designated as Hedging Instrument under GAAP \| Customer Contracts \| Swaps \| Commodity contracts:
Derivative [Line Items]
Derivative, notional amount	7,032	6,149
Derivative asset, fair value	558	350
Derivative liability, fair value	533	323
Not Designated as Hedging Instrument under GAAP \| Customer Contracts \| Futures \| Interest Rate Contracts
Derivative [Line Items]
Derivative, notional amount	965	1,235
Not Designated as Hedging Instrument under GAAP \| Customer Contracts \| Mortgage-backed commitments \| Interest Rate Contracts
Derivative [Line Items]
Derivative, notional amount	7,324	4,178
Derivative asset, fair value	36	11
Derivative liability, fair value	30	14
Not Designated as Hedging Instrument under GAAP \| Customer Contracts \| Other \| Interest Rate Contracts
Derivative [Line Items]
Derivative, notional amount	22,475	20,125
Derivative asset, fair value	157	193
Derivative liability, fair value	123	88
Not Designated as Hedging Instrument under GAAP \| Customer Contracts \| Other \| Commodity contracts:
Derivative [Line Items]
Derivative, notional amount	3,247	2,770
Derivative asset, fair value	120	61
Derivative liability, fair value	120	61
Not Designated as Hedging Instrument under GAAP \| Other Risk Management Activity \| Foreign exchange contracts and other
Derivative [Line Items]
Derivative, notional amount	10,836	10,931
Derivative asset, fair value	29	4
Derivative liability, fair value	$ 240	$ 325

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

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

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

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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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