Goodwill and Other Intangible Assets - Summary of Goodwill Assigned to Reportable Segments for Purposes of Testing for Impairment (Detail) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Goodwill [Line Items]
Goodwill	$ 8,465	$ 8,465
Commercial Bank
Goodwill [Line Items]
Goodwill	5,076
Retail Bank
Goodwill [Line Items]
Goodwill	3,089
Institutional Services and Wealth Management
Goodwill [Line Items]
Goodwill	300
All Other
Goodwill [Line Items]
Goodwill	$ 0