Borrowings - Amounts and Interest Rates of Short-term Borrowings (Detail) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Schedule Of Borrowings [Line Items]
Total	$ 1,060	$ 5,316
Weighted-average interest rate	4.39%	5.23%
Repurchase Agreements
Schedule Of Borrowings [Line Items]
Repurchase Agreements	$ 60	$ 316
Weighted-average interest rate	2.65%	3.26%
FHLB Advances
Schedule Of Borrowings [Line Items]
FHLB Advances	$ 1,000	$ 5,000
Weighted-average interest rate	4.50%	5.35%