Guarantee Arrangements, Pledged Assets and Repurchase Agreements - Summary of Pledged Assets Included in Consolidated Balance Sheet (Detail) - USD ($) $ in Millions	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Financial Instruments Owned and Pledged as Collateral [Line Items]
Interest bearing deposits with banks	$ 23,148	$ 22,625
Trading assets	22,757	21,231
Securities available-for-sale	30,030	24,937
Securities held-to-maturity	18,293	17,798
Loans, net	59,894	62,753
Other assets	6,261	6,053
Total assets	172,410	170,731	$ 168,238
Asset Pledged as Collateral
Financial Instruments Owned and Pledged as Collateral [Line Items]
Interest bearing deposits with banks	700	300
Trading assets	4,000	3,600
Securities available-for-sale	14,600	12,400
Securities held-to-maturity	12,700	9,800
Loans, net	21,600	25,100
Other assets	700	1,300
Total assets	$ 54,300	$ 52,500