Investment Securities - Amortized Cost and Fair Value of Available-for-Sale Debt and Held-to-Maturity Securities (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Available-for-Sale Debt and Other, Amortized Cost
Due in 1 year or less	$ 3,682
Due after 1 year through 5 years	16,586
Due after 5 years through 10 years	16,262
Due after 10 years	6,570
Other securities	778
Amortized Cost	43,878	$ 55,789
Available-for-Sale Debt and Other, Fair Value
Due in 1 year or less	3,666
Due after 1 year through 5 years	15,643
Due after 5 years through 10 years	13,830
Due after 10 years	5,630
Other securities	778
Fair Value	39,547	50,419
Held-to-Maturity, Amortized Cost
Due in 1 year or less	37
Due after 1 year through 5 years	3,231
Due after 5 years through 10 years	7,549
Due after 10 years	461
Other securities	0
Amortized Cost	11,278	2
Held-to-Maturity, Fair Value
Due in 1 year or less	38
Due after 1 year through 5 years	3,191
Due after 5 years through 10 years	7,286
Due after 10 years	450
Other securities	0
Fair Value	$ 10,965	$ 2