Derivative Financial Instruments - Notional Amounts and Fair Values for All Derivative Instruments Included in the Condensed Consolidated Balance Sheets (Details) - USD ($) $ in Millions	Jun. 30, 2022	Dec. 31, 2021
Derivatives, Fair Value
Derivative Assets	$ 4,135	$ 2,908
Derivative Liabilities	4,379	2,013
Amount of variation margin payment applied to derivative asset contracts	956	771
Amount of variation margin payment applied to derivative liability contracts	518	570
Designated as Hedging Instrument | Accumulated Net Gain (Loss) from Designated or Qualifying Hedges
Derivatives, Fair Value
Derivative Assets	201	522
Derivative Liabilities	86	3
Designated as Hedging Instrument | Fair Value Hedging | Accumulated Net Gain (Loss) from Designated or Qualifying Hedges
Derivatives, Fair Value
Derivative Assets	175	400
Derivative Liabilities	47	2
Designated as Hedging Instrument | Fair Value Hedging | Interest rate swap | Accumulated Net Gain (Loss) from Designated or Qualifying Hedges | Available-for-sale debt and other securities
Derivatives, Fair Value
Notional Amount		445
Derivative Assets		7
Derivative Liabilities		0
Designated as Hedging Instrument | Fair Value Hedging | Interest rate swap | Accumulated Net Gain (Loss) from Designated or Qualifying Hedges | Long-term debt
Derivatives, Fair Value
Notional Amount	2,955	1,955
Derivative Assets	175	393
Derivative Liabilities	47	2
Designated as Hedging Instrument | Cash Flow Hedging | Accumulated Net Gain (Loss) from Designated or Qualifying Hedges
Derivatives, Fair Value
Derivative Assets	26	122
Derivative Liabilities	39	1
Designated as Hedging Instrument | Cash Flow Hedging | Interest rate swap | Accumulated Net Gain (Loss) from Designated or Qualifying Hedges | Commercial and industrial
Derivatives, Fair Value
Notional Amount	18,000	8,000
Derivative Assets	4	0
Derivative Liabilities	13	1
Designated as Hedging Instrument | Cash Flow Hedging | Interest rate swap | Accumulated Net Gain (Loss) from Designated or Qualifying Hedges | Commercial Mortgage and Commercial Construction
Derivatives, Fair Value
Notional Amount	4,000	4,000
Derivative Assets	0	0
Derivative Liabilities	26	0
Designated as Hedging Instrument | Cash Flow Hedging | Interest rate floor | Accumulated Net Gain (Loss) from Designated or Qualifying Hedges | Commercial and industrial
Derivatives, Fair Value
Notional Amount	3,000	3,000
Derivative Assets	22	122
Derivative Liabilities	0	0
Not Designated as Hedging Instrument
Derivatives, Fair Value
Derivative Assets	3,934	2,386
Derivative Liabilities	4,293	2,010
Not Designated as Hedging Instrument | Risk Management and Other Business Purposes
Derivatives, Fair Value
Derivative Assets	97	147
Derivative Liabilities	227	221
Not Designated as Hedging Instrument | Risk Management and Other Business Purposes | Interest rate contracts related to MSR portfolio
Derivatives, Fair Value
Notional Amount	3,875	6,260
Derivative Assets	77	140
Derivative Liabilities	18	0
Not Designated as Hedging Instrument | Risk Management and Other Business Purposes | Forward contracts related to residential mortgage loans held for sale | Loans held for sale
Derivatives, Fair Value
Notional Amount	2,381	1,952
Derivative Assets	11	2
Derivative Liabilities	9	2
Not Designated as Hedging Instrument | Risk Management and Other Business Purposes | Swap
Derivatives, Fair Value
Notional Amount	3,196	3,545
Derivative Assets	0	0
Derivative Liabilities	199	214
Not Designated as Hedging Instrument | Risk Management and Other Business Purposes | Foreign exchange contracts
Derivatives, Fair Value
Notional Amount	176	158
Derivative Assets	3	0
Derivative Liabilities	0	1
Not Designated as Hedging Instrument | Risk Management and Other Business Purposes | Interest-only strips
Derivatives, Fair Value
Notional Amount	50
Derivative Assets	4
Derivative Liabilities	0
Not Designated as Hedging Instrument | Risk Management and Other Business Purposes | Interest rate contracts for collateral management
Derivatives, Fair Value
Notional Amount	12,000	12,000
Derivative Assets	2	5
Derivative Liabilities	1	4
Not Designated as Hedging Instrument | Risk Management and Other Business Purposes | Interest rate contracts for LIBOR transition
Derivatives, Fair Value
Notional Amount	2,372	2,372
Derivative Assets	0	0
Derivative Liabilities	0	0
Not Designated as Hedging Instrument | Customer Accommodation
Derivatives, Fair Value
Derivative Assets	3,837	2,239
Derivative Liabilities	4,066	1,789
Not Designated as Hedging Instrument | Customer Accommodation | Foreign exchange contracts
Derivatives, Fair Value
Notional Amount	25,127	23,148
Derivative Assets	532	323
Derivative Liabilities	482	297
Not Designated as Hedging Instrument | Customer Accommodation | Interest rate contracts
Derivatives, Fair Value
Notional Amount	77,211	76,061
Derivative Assets	510	578
Derivative Liabilities	992	232
Amount of variation margin payment applied to derivative asset contracts	494	104
Amount of variation margin payment applied to derivative liability contracts	25	472
Not Designated as Hedging Instrument | Customer Accommodation | Interest rate lock commitments
Derivatives, Fair Value
Notional Amount	916	673
Derivative Assets	12	12
Derivative Liabilities	1	0
Not Designated as Hedging Instrument | Customer Accommodation | Commodity contracts
Derivatives, Fair Value
Notional Amount	15,160	12,376
Derivative Assets	2,783	1,326
Derivative Liabilities	2,591	1,260
Not Designated as Hedging Instrument | Customer Accommodation | TBA securities
Derivatives, Fair Value
Notional Amount	75	55
Derivative Assets	0	0
Derivative Liabilities	$ 0	$ 0