Bank Premises and Equipment - Summary of Bank Premises and Equipment (Details) - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023
Property, Plant and Equipment [Line Items]
Accumulated depreciation and amortization	$ (3,613)	$ (3,473)
Total bank premises and equipment	2,425	2,349
Equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	2,709	2,578
Buildings
Property, Plant and Equipment [Line Items]
Property and equipment, gross	1,764	1,742
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment, gross	712	685
Land and improvements
Property, Plant and Equipment [Line Items]
Property and equipment, gross	622	618
Construction in progress
Property, Plant and Equipment [Line Items]
Property and equipment, gross	207	180
Land and improvements held for sale
Property, Plant and Equipment [Line Items]
Property and equipment, gross	10	15
Equipment held for sale
Property, Plant and Equipment [Line Items]
Property and equipment, gross	10	0
Buildings held for sale
Property, Plant and Equipment [Line Items]
Property and equipment, gross	4	4
Other property
Property, Plant and Equipment [Line Items]
Land improvements	$ 1	$ 9