Derivatives and Hedging Activities - Fair Values, Volume of Activity and Gain (Loss) Information Related to Derivative Instruments (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Derivatives, Fair Value [Line Items]
Notional Amount	$ 141,726	$ 136,020
Derivative assets, netting adjustments	(258)	(380)
Derivative Assets, net	1,523	1,796
Derivative liabilities, netting adjustments	(861)	(675)
Derivative Liabilities, net	177	140
Derivatives Not Designated as Hedging Instruments
Derivatives, Fair Value [Line Items]
Notional Amount	99,891	99,885
Derivative Assets	1,738	2,108
Derivative Liabilities	1,038	829
Interest rate \| Derivatives Designated as Hedging Instruments
Derivatives, Fair Value [Line Items]
Notional Amount	41,835	36,135
Derivative Assets	44	70
Derivative Liabilities	6	(3)
Interest rate \| Derivatives Not Designated as Hedging Instruments
Derivatives, Fair Value [Line Items]
Notional Amount	76,937	78,424
Derivative Assets	971	1,514
Derivative Liabilities	312	291
Foreign exchange \| Derivatives Not Designated as Hedging Instruments
Derivatives, Fair Value [Line Items]
Notional Amount	6,412	6,385
Derivative Assets	95	109
Derivative Liabilities	84	103
Commodity \| Derivatives Not Designated as Hedging Instruments
Derivatives, Fair Value [Line Items]
Notional Amount	11,126	9,702
Derivative Assets	638	426
Derivative Liabilities	620	408
Credit \| Derivatives Not Designated as Hedging Instruments
Derivatives, Fair Value [Line Items]
Notional Amount	392	423
Derivative Assets	1	1
Derivative Liabilities	8	11
Other
Derivatives, Fair Value [Line Items]
Derivative Assets	8
Other \| Derivatives Not Designated as Hedging Instruments
Derivatives, Fair Value [Line Items]
Notional Amount	5,024	4,951
Derivative Assets	33	58
Derivative Liabilities	14	16
Net derivatives
Derivatives, Fair Value [Line Items]
Notional Amount	141,726	136,020
Derivative Assets, net	1,524	1,798
Derivative Liabilities, net	183	151
Other collateral
Derivatives, Fair Value [Line Items]
Notional Amount	0	0
Derivative Assets, net	(1)	(2)
Derivative Liabilities, net	$ (6)	$ (11)

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