Investment Securities - Additional Information (Details) - USD ($) $ in Millions	1 Months Ended	3 Months Ended
	Jan. 31, 2024	Mar. 31, 2025	Mar. 31, 2024	Dec. 31, 2024
Investments, Unrealized Loss Position
Accrued interest receivables on investment securities		$ 162		$ 162
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
Impairment losses		0	$ 5
Investment securities, fair value		29,300		30,000
Unrealized losses		3,707		4,337
Non-rated Securities
Investments, Unrealized Loss Position
Unrealized losses		$ 30		$ 34