Other Short-Term Borrowings - Summary of Other Short-Term Borrowings (Details) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Short-Term Debt [Abstract]
FHLB advances	$ 2,500	$ 2,500
Securities sold under repurchase agreements	336	330
Derivative collateral	0	3
Other borrowed money	30	28
Other short-term borrowings	$ 2,866	$ 2,861