Derivatives and Hedging Activities - Fair Values, Volume of Activity and Gain (Loss) Information Related to Derivative Instruments (Details) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Derivatives, Fair Value [Line Items]
Notional Amount	$ 135,570	$ 136,020
Derivative assets, netting adjustments	(302)	(380)
Derivative Assets, net	2,552	1,796
Derivative liabilities, netting adjustments	(1,911)	(675)
Derivative Liabilities, net	230	140
Derivatives Not Designated as Hedging Instruments
Derivatives, Fair Value [Line Items]
Notional Amount	99,147	99,885
Derivative Assets	2,810	2,108
Derivative Liabilities	2,160	829
Interest rate \| Derivatives Designated as Hedging Instruments
Derivatives, Fair Value [Line Items]
Notional Amount	36,423	36,135
Derivative Assets	45	70
Derivative Liabilities	11	(3)
Interest rate \| Derivatives Not Designated as Hedging Instruments
Derivatives, Fair Value [Line Items]
Notional Amount	72,688	78,424
Derivative Assets	909	1,514
Derivative Liabilities	262	291
Foreign exchange \| Derivatives Not Designated as Hedging Instruments
Derivatives, Fair Value [Line Items]
Notional Amount	7,378	6,385
Derivative Assets	80	109
Derivative Liabilities	75	103
Commodity \| Derivatives Not Designated as Hedging Instruments
Derivatives, Fair Value [Line Items]
Notional Amount	15,090	9,702
Derivative Assets	1,799	426
Derivative Liabilities	1,805	408
Credit \| Derivatives Not Designated as Hedging Instruments
Derivatives, Fair Value [Line Items]
Notional Amount	339	423
Derivative Assets	0	1
Derivative Liabilities	7	11
Other
Derivatives, Fair Value [Line Items]
Derivative Assets	6
Other \| Derivatives Not Designated as Hedging Instruments
Derivatives, Fair Value [Line Items]
Notional Amount	3,652	4,951
Derivative Assets	22	58
Derivative Liabilities	11	16
Net derivatives
Derivatives, Fair Value [Line Items]
Notional Amount	135,570	136,020
Derivative Assets, net	2,553	1,798
Derivative Liabilities, net	260	151
Other collateral
Derivatives, Fair Value [Line Items]
Notional Amount	0	0
Derivative Assets, net	(1)	(2)
Derivative Liabilities, net	$ (30)	$ (11)

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