Net Interest Income (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Interest income:
Interest-bearing deposits with banks	$ 696	$ 768
Investment securities:
Investment securities available-for-sale	706	724
Investment securities held-to-maturity	207	242
Total investment securities	913	966
Securities purchased under resale agreements	152	165
Trading account assets	1	0
Loans	543	557
Other interest-earning assets	346	466
Total interest income	2,651	2,922
Interest expense:
Interest-bearing deposits	1,353	1,566
Securities sold under repurchase agreements	2	51
Other short-term borrowings	39	135
Long-term debt	286	297
Other interest-bearing liabilities	136	159
Total interest expense	1,816	2,208
Net interest income	$ 835	$ 714