Derivative Financial Instruments - Classifications and Hedging Relationships (Details) - USD ($) $ in Millions	Jun. 30, 2024	Dec. 31, 2023
Derivative Instruments, Notional, Fair Value Assets and Liabilities[Line Items]
Notional Amount	$ 362,436	$ 365,959
Derivative Asset, Fair Value, Gross	3,238	2,828
Derivative Liability, Fair Value, Gross	(5,320)	(4,682)
Derivative Asset [Abstract]
Amounts subject to master netting arrangements and exchange traded derivatives	(1,647)	(1,268)
Cash collateral (received) posted for amounts subject to master netting arrangements	(496)	(609)
Net Amount in Consolidated Balance Sheets	1,095	951
Derivative Liability [Abstract]
Amounts subject to master netting arrangements and exchange traded derivatives	1,647	1,268
Cash collateral (received) posted for amounts subject to master netting arrangements	934	817
Net amount	(2,739)	(2,597)
Cash flow hedges | Interest rate contracts | Swap | Commercial loans
Derivative Instruments, Notional, Fair Value Assets and Liabilities[Line Items]
Notional Amount	25,538	17,673
Derivative Asset, Fair Value, Gross	0	0
Derivative Liability, Fair Value, Gross	0	0
Fair value hedges | Interest rate contracts
Derivative Instruments, Notional, Fair Value Assets and Liabilities[Line Items]
Notional Amount	30,558	38,446
Derivative Asset, Fair Value, Gross	0	0
Derivative Liability, Fair Value, Gross	0	0
Fair value hedges | Interest rate contracts | Swap | Long-term debt
Derivative Instruments, Notional, Fair Value Assets and Liabilities[Line Items]
Notional Amount	17,768	14,268
Derivative Asset, Fair Value, Gross	0	0
Derivative Liability, Fair Value, Gross	0	0
Fair value hedges | Interest rate contracts | Swap | AFS securities
Derivative Instruments, Notional, Fair Value Assets and Liabilities[Line Items]
Notional Amount	11,810	24,178
Derivative Asset, Fair Value, Gross	0	0
Derivative Liability, Fair Value, Gross	0	0
Fair value hedges | Interest rate contracts | Swap | U.S. Treasury
Derivative Instruments, Notional, Fair Value Assets and Liabilities[Line Items]
Notional Amount	980	0
Derivative Asset, Fair Value, Gross	0	0
Derivative Liability, Fair Value, Gross	0	0
Not designated as hedges
Derivative Instruments, Notional, Fair Value Assets and Liabilities[Line Items]
Notional Amount	306,340	309,840
Derivative Asset, Fair Value, Gross	3,238	2,828
Derivative Liability, Fair Value, Gross	(5,320)	(4,682)
Not designated as hedges | Client-related and other risk management
Derivative Instruments, Notional, Fair Value Assets and Liabilities[Line Items]
Notional Amount	267,256	274,326
Derivative Asset, Fair Value, Gross	3,124	2,725
Derivative Liability, Fair Value, Gross	(5,223)	(4,545)
Not designated as hedges | Client-related and other risk management | Interest rate contracts | Swap
Derivative Instruments, Notional, Fair Value Assets and Liabilities[Line Items]
Notional Amount	150,670	154,692
Derivative Asset, Fair Value, Gross	560	637
Derivative Liability, Fair Value, Gross	(2,091)	(1,926)
Not designated as hedges | Client-related and other risk management | Interest rate contracts | Options
Derivative Instruments, Notional, Fair Value Assets and Liabilities[Line Items]
Notional Amount	26,820	34,593
Derivative Asset, Fair Value, Gross	64	114
Derivative Liability, Fair Value, Gross	(86)	(106)
Not designated as hedges | Client-related and other risk management | Interest rate contracts | Forward commitments
Derivative Instruments, Notional, Fair Value Assets and Liabilities[Line Items]
Notional Amount	554	178
Derivative Asset, Fair Value, Gross	1	0
Derivative Liability, Fair Value, Gross	(3)	(11)
Not designated as hedges | Client-related and other risk management | Interest rate contracts | Other
Derivative Instruments, Notional, Fair Value Assets and Liabilities[Line Items]
Notional Amount	4,012	3,033
Derivative Asset, Fair Value, Gross	0	0
Derivative Liability, Fair Value, Gross	0	0
Not designated as hedges | Client-related and other risk management | Equity contracts
Derivative Instruments, Notional, Fair Value Assets and Liabilities[Line Items]
Notional Amount	42,809	39,561
Derivative Asset, Fair Value, Gross	1,763	1,164
Derivative Liability, Fair Value, Gross	(2,382)	(1,733)
Not designated as hedges | Client-related and other risk management | Credit Contract | Trading assets
Derivative Instruments, Notional, Fair Value Assets and Liabilities[Line Items]
Notional Amount	610	100
Derivative Asset, Fair Value, Gross	0	0
Derivative Liability, Fair Value, Gross	0	0
Not designated as hedges | Client-related and other risk management | Credit Contract | Loans and leases
Derivative Instruments, Notional, Fair Value Assets and Liabilities[Line Items]
Notional Amount	325	225
Derivative Asset, Fair Value, Gross	0	0
Derivative Liability, Fair Value, Gross	0	0
Not designated as hedges | Client-related and other risk management | Credit Contract | Risk participation agreements
Derivative Instruments, Notional, Fair Value Assets and Liabilities[Line Items]
Notional Amount	7,443	7,499
Derivative Asset, Fair Value, Gross	0	0
Derivative Liability, Fair Value, Gross	(2)	(3)
Not designated as hedges | Client-related and other risk management | Credit Contract | Total Return Swap
Derivative Instruments, Notional, Fair Value Assets and Liabilities[Line Items]
Notional Amount	1,577	1,598
Derivative Asset, Fair Value, Gross	53	41
Derivative Liability, Fair Value, Gross	(5)	(7)
Not designated as hedges | Client-related and other risk management | Foreign exchange contracts
Derivative Instruments, Notional, Fair Value Assets and Liabilities[Line Items]
Notional Amount	21,750	24,480
Derivative Asset, Fair Value, Gross	221	256
Derivative Liability, Fair Value, Gross	(206)	(256)
Not designated as hedges | Client-related and other risk management | Commodity Contract
Derivative Instruments, Notional, Fair Value Assets and Liabilities[Line Items]
Notional Amount	10,686	8,367
Derivative Asset, Fair Value, Gross	462	513
Derivative Liability, Fair Value, Gross	(448)	(503)
Not designated as hedges | Mortgage banking | Interest rate contracts
Derivative Instruments, Notional, Fair Value Assets and Liabilities[Line Items]
Notional Amount	4,629	2,783
Derivative Asset, Fair Value, Gross	22	20
Derivative Liability, Fair Value, Gross	(14)	(27)
Not designated as hedges | Mortgage banking | Interest rate contracts | Swap
Derivative Instruments, Notional, Fair Value Assets and Liabilities[Line Items]
Notional Amount	354	105
Derivative Asset, Fair Value, Gross	0	0
Derivative Liability, Fair Value, Gross	0	0
Not designated as hedges | Mortgage banking | Interest rate contracts | Options
Derivative Instruments, Notional, Fair Value Assets and Liabilities[Line Items]
Notional Amount	400	400
Derivative Asset, Fair Value, Gross	1	3
Derivative Liability, Fair Value, Gross	0	0
Not designated as hedges | Mortgage banking | Interest rate contracts | Other
Derivative Instruments, Notional, Fair Value Assets and Liabilities[Line Items]
Notional Amount	460	94
Derivative Asset, Fair Value, Gross	1	0
Derivative Liability, Fair Value, Gross	0	0
Not designated as hedges | Mortgage banking | Interest rate contracts | Interest rate lock commitments
Derivative Instruments, Notional, Fair Value Assets and Liabilities[Line Items]
Notional Amount	1,306	746
Derivative Asset, Fair Value, Gross	3	5
Derivative Liability, Fair Value, Gross	(9)	(10)
Not designated as hedges | Mortgage banking | Interest rate contracts | When issued securities, forward rate agreements and forward commitments
Derivative Instruments, Notional, Fair Value Assets and Liabilities[Line Items]
Notional Amount	2,109	1,438
Derivative Asset, Fair Value, Gross	17	12
Derivative Liability, Fair Value, Gross	(5)	(17)
Not designated as hedges | Loan Servicing Rights | Interest rate contracts
Derivative Instruments, Notional, Fair Value Assets and Liabilities[Line Items]
Notional Amount	34,455	32,731
Derivative Asset, Fair Value, Gross	92	83
Derivative Liability, Fair Value, Gross	(83)	(110)
Not designated as hedges | Loan Servicing Rights | Interest rate contracts | Swap
Derivative Instruments, Notional, Fair Value Assets and Liabilities[Line Items]
Notional Amount	16,948	15,252
Derivative Asset, Fair Value, Gross	0	0
Derivative Liability, Fair Value, Gross	0	0
Not designated as hedges | Loan Servicing Rights | Interest rate contracts | Options
Derivative Instruments, Notional, Fair Value Assets and Liabilities[Line Items]
Notional Amount	13,674	14,854
Derivative Asset, Fair Value, Gross	84	75
Derivative Liability, Fair Value, Gross	(78)	(109)
Not designated as hedges | Loan Servicing Rights | Interest rate contracts | Other
Derivative Instruments, Notional, Fair Value Assets and Liabilities[Line Items]
Notional Amount	2,583	1,692
Derivative Asset, Fair Value, Gross	2	0
Derivative Liability, Fair Value, Gross	(3)	(1)
Not designated as hedges | Loan Servicing Rights | Interest rate contracts | When issued securities, forward rate agreements and forward commitments
Derivative Instruments, Notional, Fair Value Assets and Liabilities[Line Items]
Notional Amount	1,250	933
Derivative Asset, Fair Value, Gross	6	8
Derivative Liability, Fair Value, Gross	$ (2)	$ 0