Derivative Financial Instruments - Notional Amounts and Fair Values for All Derivative Instruments Included in the Condensed Consolidated Balance Sheets (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Derivatives, Fair Value
Derivative assets, fair value, gross assets	$ 2,470	$ 2,672
Total derivative assets	2,472	2,677
Derivative liabilities, fair value, gross liabilities	2,798	2,999
Total derivative liabilities	2,798	2,999
Amount of variation margin payment applied to derivative asset contracts	257	335
Amount of variation margin payment applied to derivative liability contracts	45	58
Designated as Hedging Instrument | Accumulated Net Gain (Loss) from Designated or Qualifying Hedges
Derivatives, Fair Value
Derivative assets, fair value, gross assets	7	10
Derivative liabilities, fair value, gross liabilities	16	45
Designated as Hedging Instrument | Fair Value Hedging | Accumulated Net Gain (Loss) from Designated or Qualifying Hedges
Derivatives, Fair Value
Derivative assets, fair value, gross assets	1	0
Derivative liabilities, fair value, gross liabilities	12	32
Designated as Hedging Instrument | Fair Value Hedging | Interest rate swaps | Accumulated Net Gain (Loss) from Designated or Qualifying Hedges | Long-term debt
Derivatives, Fair Value
Notional Amount	4,955	5,955
Derivative assets, fair value, gross assets	1	0
Derivative liabilities, fair value, gross liabilities	12	32
Designated as Hedging Instrument | Cash Flow Hedging | Accumulated Net Gain (Loss) from Designated or Qualifying Hedges
Derivatives, Fair Value
Derivative assets, fair value, gross assets	6	10
Derivative liabilities, fair value, gross liabilities	4	13
Designated as Hedging Instrument | Cash Flow Hedging | Interest rate swaps | Accumulated Net Gain (Loss) from Designated or Qualifying Hedges | Commercial and Industrial
Derivatives, Fair Value
Notional Amount	11,000	8,000
Derivative assets, fair value, gross assets	2	2
Derivative liabilities, fair value, gross liabilities	4	11
Designated as Hedging Instrument | Cash Flow Hedging | Interest rate swaps | Accumulated Net Gain (Loss) from Designated or Qualifying Hedges | Commercial Mortgage and Commercial Construction
Derivatives, Fair Value
Notional Amount		4,000
Derivative assets, fair value, gross assets		1
Derivative liabilities, fair value, gross liabilities		1
Designated as Hedging Instrument | Cash Flow Hedging | Interest rate swap - forward starting | Accumulated Net Gain (Loss) from Designated or Qualifying Hedges | Commercial and Industrial
Derivatives, Fair Value
Notional Amount	1,000	6,000
Derivative assets, fair value, gross assets	1	6
Derivative liabilities, fair value, gross liabilities	0	1
Designated as Hedging Instrument | Cash Flow Hedging | Interest rate swap - forward starting | Accumulated Net Gain (Loss) from Designated or Qualifying Hedges | Commercial Mortgage and Commercial Construction
Derivatives, Fair Value
Notional Amount	4,000
Derivative assets, fair value, gross assets	3
Derivative liabilities, fair value, gross liabilities	0
Designated as Hedging Instrument | Cash Flow Hedging | Interest rate floors | Accumulated Net Gain (Loss) from Designated or Qualifying Hedges | Commercial and Industrial
Derivatives, Fair Value
Notional Amount		3,000
Derivative assets, fair value, gross assets		1
Derivative liabilities, fair value, gross liabilities		0
Not Designated as Hedging Instrument
Derivatives, Fair Value
Total derivative assets	2,465	2,667
Total derivative liabilities	2,782	2,954
Not Designated as Hedging Instrument | Risk Management and Other Business Purposes
Derivatives, Fair Value
Derivative assets, fair value, gross assets	15	83
Derivative liabilities, fair value, gross liabilities	174	178
Not Designated as Hedging Instrument | Risk Management and Other Business Purposes | Interest rate contracts related to MSR portfolio
Derivatives, Fair Value
Notional Amount	3,135	3,205
Derivative assets, fair value, gross assets	4	81
Derivative liabilities, fair value, gross liabilities	4	0
Not Designated as Hedging Instrument | Risk Management and Other Business Purposes | Forward contracts related to residential mortgage loans measured at fair value | Loans held for sale
Derivatives, Fair Value
Notional Amount		650
Derivative assets, fair value, gross assets	8	0
Derivative liabilities, fair value, gross liabilities	0	5
Not Designated as Hedging Instrument | Risk Management and Other Business Purposes | Swap
Derivatives, Fair Value
Notional Amount	2,465	4,178
Derivative assets, fair value, gross assets	0	0
Derivative liabilities, fair value, gross liabilities	170	168
Not Designated as Hedging Instrument | Risk Management and Other Business Purposes | Interest-only strips
Derivatives, Fair Value
Notional Amount	30	39
Derivative assets, fair value, gross assets	0	1
Derivative liabilities, fair value, gross liabilities	0	0
Not Designated as Hedging Instrument | Risk Management and Other Business Purposes | Interest rate contracts for collateral management
Derivatives, Fair Value
Notional Amount	1,000	5,000
Derivative assets, fair value, gross assets	1	1
Derivative liabilities, fair value, gross liabilities	0	1
Not Designated as Hedging Instrument | Risk Management and Other Business Purposes | Interest rate contracts for LIBOR transition
Derivatives, Fair Value
Notional Amount	597	597
Derivative assets, fair value, gross assets	0	0
Derivative liabilities, fair value, gross liabilities	0	0
Not Designated as Hedging Instrument | Risk Management and Other Business Purposes | Other
Derivatives, Fair Value
Notional Amount	43	30
Derivative assets, fair value, gross assets	0	0
Derivative liabilities, fair value, gross liabilities	0	0
Not Designated as Hedging Instrument | Risk Management and Other Business Purposes | Foreign exchange contracts
Derivatives, Fair Value
Notional Amount	104	190
Derivative assets, fair value, gross assets	2	0
Derivative liabilities, fair value, gross liabilities	0	4
Not Designated as Hedging Instrument | Customer Accommodation
Derivatives, Fair Value
Total derivative assets	2,450	2,584
Total derivative liabilities	2,608	2,776
Not Designated as Hedging Instrument | Customer Accommodation | Interest rate contracts for LIBOR transition
Derivatives, Fair Value
Notional Amount		675
Not Designated as Hedging Instrument | Customer Accommodation | Interest rate contracts
Derivatives, Fair Value
Notional Amount	87,928	95,079
Derivative assets, fair value, gross assets	708	885
Derivative liabilities, fair value, gross liabilities	924	1,162
Not Designated as Hedging Instrument | Customer Accommodation | Interest rate lock commitments
Derivatives, Fair Value
Notional Amount	264	252
Derivative assets, not subject to master netting arrangement	2	5
Derivative liabilities, not subject to master netting arrangement	0	0
Not Designated as Hedging Instrument | Customer Accommodation | Commodity contracts
Derivatives, Fair Value
Notional Amount	16,889	17,621
Derivative assets, fair value, gross assets	575	1,051
Derivative liabilities, fair value, gross liabilities	564	1,018
Not Designated as Hedging Instrument | Customer Accommodation | TBA securities
Derivatives, Fair Value
Notional Amount	44	27
Derivative assets, fair value, gross assets	0	0
Derivative liabilities, fair value, gross liabilities	0	0
Not Designated as Hedging Instrument | Customer Accommodation | Foreign exchange contracts
Derivatives, Fair Value
Notional Amount	38,640	37,734
Derivative assets, fair value, gross assets	1,165	643
Derivative liabilities, fair value, gross liabilities	$ 1,120	$ 596