Securities - Narrative (Detail) - USD ($)	3 Months Ended	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Debt Securities, Available-for-sale [Line Items]
Securities available-for-sale, allowance for credit losses	$ 0	$ 0	$ 0
Securities held-to-maturity, allowance for credit losses	0	0	0
Securities held-to-maturity, past due	15,076,000,000	15,076,000,000	7,317,000,000
Securities held-to-maturity, nonaccrual	0	0	0
Debt Securities, Available-for-Sale, Realized Loss		(246,000,000)	(6,000,000)	$ (86,000,000)
Equity securities without readily determinable fair values, impairment loss adjustment		5,000,000	3,000,000	$ 3,000,000
U.S. Government agency issued or guaranteed
Debt Securities, Available-for-sale [Line Items]
Debt Securities, available-for-sale, carrying calue	960,000,000	960,000,000
Debt Securities, Available-for-Sale, Realized Loss	(246,000,000)
Past Due
Debt Securities, Available-for-sale [Line Items]
Securities held-to-maturity, past due	0	0	0
Other assets
Debt Securities, Available-for-sale [Line Items]
Federal Home Loan Bank stock	95,000,000	95,000,000	95,000,000
Federal Reserve Bank stock	$ 438,000,000	$ 438,000,000	$ 498,000,000