Securities - Schedule of Securities by Maturity (Details) - USD ($) $ in Millions	Sep. 30, 2025	Dec. 31, 2024
Securities Available for Sale, Amortized Cost
Due in one year or less	$ 3,023
Due after one through five years	11,115
Due after five through ten years	21,322
Due after ten years	7,433
Total	42,893
Securities Available for Sale, Fair Value
Due in one year or less	3,030
Due after one through five years	10,811
Due after five through ten years	19,646
Due after ten years	6,969
Total	40,456	$ 37,707
Held-to-Maturity Securities, Amortized Cost
Due in one year or less	562
Due after one through five years	2,153
Due after five through ten years	3,603
Due after ten years	1,191
Total	7,509	7,395
Held-to-Maturity Securities, Fair Value
Due in one year or less	555
Due after one through five years	2,091
Due after five through ten years	3,460
Due after ten years	1,058
Total	$ 7,164	$ 6,837