Expenses - Schedule of Expenses (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2026	Mar. 31, 2025	Dec. 31, 2025
Other Expenses [Abstract]
Professional services	$ 104	$ 110
Amortization of other intangible assets	57	54	$ 223
Sales advertising and public relations	34	25
Regulatory fees and assessments	12	13
Bank operations	10	13
Securities processing	10	4
Donations	0	4
Other	122	107
Total other expenses	$ 349	$ 330