Investment Securities - Additional Information (Details) - USD ($) $ in Millions	1 Months Ended
	Jan. 31, 2024	Dec. 31, 2024	Dec. 31, 2023
Investments, Unrealized Loss Position
Accrued interest receivables on investment securities		$ 162	$ 146
Transfer of available-for-sale securities to held-to-maturity	$ 12,600
OCI, available-for-sale debt securities transferred to held-to-maturity, pretax unrealized losses	$ 994
Securities with a fair value, pledged as collateral		30,000	25,200
Unrealized losses		4,337	5,379
AOCI, Accumulated Gain (Loss), Debt Securities, Available-for-Sale Transferred to Held-to-Maturity, Parent
Investments, Unrealized Loss Position
AOCI offset, unamortized portion of unrealized losses on securities		865
Non-rated Securities
Investments, Unrealized Loss Position
Unrealized losses		$ 34	$ 45