Loans and Leases and the Allowance for Credit Losses - Summary of Payment Status of Loans Modified (Parenthetical) (Detail) $ in Millions	Mar. 31, 2024 USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
30-89 Days Past Due	$ 121
Past Due 90 Days or More	64
Guaranteed by Government-Related Entities [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
30-89 Days Past Due	30
Past Due 90 Days or More	$ 27