Fair Value of Assets and Liabilities - Schedule Of Assets And Liabilities Measured At Fair Value On A Recurring Basis (Details) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Trading securities	$ 1,161	$ 1,412
Loans held-for-sale	84	68
Securities available for sale at fair value	8,148	8,391
Recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Loans held-for-sale	84	68
Securities available for sale at fair value	8,148	8,391
Total other assets	791	713
Total assets	10,184	10,584
Total other liabilities	816	699
Total liabilities	1,283	1,208
Level 1 | Recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Loans held-for-sale	0	0
Securities available for sale at fair value	0	0
Total other assets	146	145
Total assets	146	145
Total other liabilities	4	10
Total liabilities	4	10
Level 2 | Recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Loans held-for-sale	70	42
Securities available for sale at fair value	8,148	8,391
Total other assets	645	568
Total assets	10,005	10,400
Total other liabilities	792	666
Total liabilities	1,259	1,175
Level 3 | Recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Loans held-for-sale	14	26
Securities available for sale at fair value	0	0
Total other assets	0	0
Total assets	33	39
Total other liabilities	20	23
Total liabilities	20	23
Deferred compensation mutual funds | Recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Total other assets	107	102
Deferred compensation mutual funds | Level 1 | Recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Total other assets	107	102
Deferred compensation mutual funds | Level 2 | Recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Total other assets	0	0
Deferred compensation mutual funds | Level 3 | Recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Total other assets	0	0
Equity, mutual funds, and other | Recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Total other assets	34	34
Equity, mutual funds, and other | Level 1 | Recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Total other assets	34	34
Equity, mutual funds, and other | Level 2 | Recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Total other assets	0	0
Equity, mutual funds, and other | Level 3 | Recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Total other assets	0	0
Derivatives, forwards and futures | Recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Total other assets	5	9
Total other liabilities	4	10
Derivatives, forwards and futures | Level 1 | Recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Total other assets	5	9
Total other liabilities	4	10
Derivatives, forwards and futures | Level 2 | Recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Total other assets	0	0
Total other liabilities	0	0
Derivatives, forwards and futures | Level 3 | Recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Total other assets	0	0
Total other liabilities	0	0
Derivatives, interest rate contracts | Recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Total other assets	645	568
Total other liabilities	791	666
Derivatives, interest rate contracts | Level 1 | Recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Total other assets	0	0
Total other liabilities	0	0
Derivatives, interest rate contracts | Level 2 | Recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Total other assets	645	568
Total other liabilities	791	666
Derivatives, interest rate contracts | Level 3 | Recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Total other assets	0	0
Total other liabilities	0	0
Derivatives, other | Recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Total other liabilities	21	23
Derivatives, other | Level 1 | Recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Total other liabilities	0	0
Derivatives, other | Level 2 | Recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Total other liabilities	1	0
Derivatives, other | Level 3 | Recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Total other liabilities	20	23
Government agency issued MBS | Recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Securities available for sale at fair value	4,351	4,484
Government agency issued MBS | Level 1 | Recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Securities available for sale at fair value	0	0
Government agency issued MBS | Level 2 | Recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Securities available for sale at fair value	4,351	4,484
Government agency issued MBS | Level 3 | Recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Securities available for sale at fair value	0	0
Government agency issued CMO | Recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Securities available for sale at fair value	2,085	2,146
Government agency issued CMO | Level 1 | Recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Securities available for sale at fair value	0	0
Government agency issued CMO | Level 2 | Recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Securities available for sale at fair value	2,085	2,146
Government agency issued CMO | Level 3 | Recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Securities available for sale at fair value	0	0
Other U.S. government agencies | Recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Securities available for sale at fair value	1,133	1,172
Other U.S. government agencies | Level 1 | Recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Securities available for sale at fair value	0	0
Other U.S. government agencies | Level 2 | Recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Securities available for sale at fair value	1,133	1,172
Other U.S. government agencies | Level 3 | Recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Securities available for sale at fair value	0	0
States and municipalities | Recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Securities available for sale at fair value	579	589
States and municipalities | Level 1 | Recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Securities available for sale at fair value	0	0
States and municipalities | Level 2 | Recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Securities available for sale at fair value	579	589
States and municipalities | Level 3 | Recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Securities available for sale at fair value	0	0
Specialty Banking | Recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Trading securities	1,161	1,412
Total trading liabilities	467	509
Specialty Banking | Level 1 | Recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Trading securities	0	0
Total trading liabilities	0	0
Specialty Banking | Level 2 | Recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Trading securities	1,142	1,399
Total trading liabilities	467	509
Specialty Banking | Level 3 | Recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Trading securities	19	13
Total trading liabilities	0	0
Specialty Banking | U.S. treasuries | Recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Trading securities	6	3
Total trading liabilities	379	426
Specialty Banking | U.S. treasuries | Level 1 | Recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Trading securities	0	0
Total trading liabilities	0	0
Specialty Banking | U.S. treasuries | Level 2 | Recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Trading securities	6	3
Total trading liabilities	379	426
Specialty Banking | U.S. treasuries | Level 3 | Recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Trading securities	0	0
Total trading liabilities	0	0
Specialty Banking | Government agency issued MBS | Recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Trading securities	78	114
Total trading liabilities		1
Specialty Banking | Government agency issued MBS | Level 1 | Recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Trading securities	0	0
Total trading liabilities		0
Specialty Banking | Government agency issued MBS | Level 2 | Recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Trading securities	78	114
Total trading liabilities		1
Specialty Banking | Government agency issued MBS | Level 3 | Recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Trading securities	0	0
Total trading liabilities		0
Specialty Banking | Government agency issued CMO | Recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Trading securities	178	336
Specialty Banking | Government agency issued CMO | Level 1 | Recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Trading securities	0	0
Specialty Banking | Government agency issued CMO | Level 2 | Recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Trading securities	178	336
Specialty Banking | Government agency issued CMO | Level 3 | Recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Trading securities	0	0
Specialty Banking | Other U.S. government agencies | Recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Trading securities	233	152
Specialty Banking | Other U.S. government agencies | Level 1 | Recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Trading securities	0	0
Specialty Banking | Other U.S. government agencies | Level 2 | Recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Trading securities	233	152
Specialty Banking | Other U.S. government agencies | Level 3 | Recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Trading securities	0	0
Specialty Banking | States and municipalities | Recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Trading securities	21	17
Specialty Banking | States and municipalities | Level 1 | Recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Trading securities	0	0
Specialty Banking | States and municipalities | Level 2 | Recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Trading securities	21	17
Specialty Banking | States and municipalities | Level 3 | Recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Trading securities	0	0
Specialty Banking | Corporate and other debt | Recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Trading securities	626	777
Total trading liabilities	88	82
Specialty Banking | Corporate and other debt | Level 1 | Recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Trading securities	0	0
Total trading liabilities	0	0
Specialty Banking | Corporate and other debt | Level 2 | Recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Trading securities	626	777
Total trading liabilities	88	82
Specialty Banking | Corporate and other debt | Level 3 | Recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Trading securities	0	0
Total trading liabilities	0	0
Specialty Banking | Interest-only strips | Recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Trading securities	19	13
Specialty Banking | Interest-only strips | Level 1 | Recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Trading securities	0	0
Specialty Banking | Interest-only strips | Level 2 | Recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Trading securities	0	0
Specialty Banking | Interest-only strips | Level 3 | Recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Trading securities	$ 19	$ 13