Net Interest Income - Components of Interest Revenue and Interest Expense (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Interest income:
Interest-bearing deposits with banks	$ 2,911	$ 3,634	$ 2,869
Investment securities:
Investment securities available-for-sale	2,995	2,680	1,744
Investment securities held-to-maturity	917	1,090	1,262
Total investment securities	3,912	3,770	3,006
Securities purchased under resale agreements	672	686	312
Trading account assets	4	0	0
Loans	2,286	2,271	1,862
Other interest-earning assets	1,859	1,616	1,131
Total interest income	11,644	11,977	9,180
Interest expense:
Interest-bearing deposits	6,382	6,627	4,991
Securities sold under repurchase agreements	95	156	34
Federal funds purchased	0	0	3
Other short-term borrowings	434	577	40
Long-term debt	1,230	1,086	888
Other interest-bearing liabilities	543	608	465
Total interest expense	8,684	9,054	6,421
Net interest income	$ 2,960	$ 2,923	$ 2,759