Revenue from Contracts with Customers - Summary of Sources of Noninterest Income that are Subject to Revenue Recognition Accounting Guidance (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Disaggregation Of Revenue [Line Items]
Brokerage services income	$ 29	$ 24
Other revenues from operations:
Total other income	580	587
Service Charges on Deposit Accounts [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	124	113
Trust Income [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	160	194
ASU 2014-09 [Member]
Disaggregation Of Revenue [Line Items]
Brokerage services income	29	24
Other revenues from operations:
Merchant discount and credit card interchange fees	37	37
Other	17	15
Total other income	367	383
ASU 2014-09 [Member] | Service Charges on Deposit Accounts [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	124	113
ASU 2014-09 [Member] | Trust Income [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	160	194
ASU 2014-09 [Member] | Commercial Bank [Member]
Disaggregation Of Revenue [Line Items]
Brokerage services income	2	2
Other revenues from operations:
Merchant discount and credit card interchange fees	17	17
Other	8	6
Total other income	68	59
ASU 2014-09 [Member] | Commercial Bank [Member] | Service Charges on Deposit Accounts [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	40	34
ASU 2014-09 [Member] | Commercial Bank [Member] | Trust Income [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	1
ASU 2014-09 [Member] | Retail Bank [Member]
Other revenues from operations:
Merchant discount and credit card interchange fees	20	20
Other	7	8
Total other income	111	107
ASU 2014-09 [Member] | Retail Bank [Member] | Service Charges on Deposit Accounts [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	84	79
ASU 2014-09 [Member] | Institutional Services and Wealth Management [ Member]
Disaggregation Of Revenue [Line Items]
Brokerage services income	27	22
Other revenues from operations:
Other	2	1
Total other income	188	217
ASU 2014-09 [Member] | Institutional Services and Wealth Management [ Member] | Trust Income [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	$ 159	$ 194