Revenue from Contracts with Customers - Summary of Sources of Noninterest Income that are Subject to Revenue Recognition Accounting Guidance (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	$ 397	$ 367
Service charges on deposit accounts
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	133	124
Trust income
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	177	160
Brokerage services income
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	32	29
Merchant discount and credit card interchange fees
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	37	37
Other
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	18	17
Commercial Bank
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	72	68
Commercial Bank | Service charges on deposit accounts
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	45	40
Commercial Bank | Trust income
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	1	1
Commercial Bank | Brokerage services income
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	1	2
Commercial Bank | Merchant discount and credit card interchange fees
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	16	17
Commercial Bank | Other
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	9	8
Retail Bank
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	116	111
Retail Bank | Service charges on deposit accounts
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	88	84
Retail Bank | Trust income
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	0	0
Retail Bank | Brokerage services income
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	0	0
Retail Bank | Merchant discount and credit card interchange fees
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	21	20
Retail Bank | Other
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	7	7
Institutional Services and Wealth Management
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	209	188
Institutional Services and Wealth Management | Service charges on deposit accounts
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	0	0
Institutional Services and Wealth Management | Trust income
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	176	159
Institutional Services and Wealth Management | Brokerage services income
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	31	27
Institutional Services and Wealth Management | Merchant discount and credit card interchange fees
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	0	0
Institutional Services and Wealth Management | Other
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	$ 2	$ 2