INVESTMENT SECURITIES - Schedule of Contractual Maturities of Debt Securities Available for Sale (Details) - USD ($) $ in Millions	Dec. 31, 2025	Dec. 31, 2024
Amortized Cost
Due within one year	$ 1,003
Due after one year through five years	4,407
Due after five years through ten years	4,037
Due after ten years	1,307
Mortgage and asset-backed securities	6,263
Amortized Cost	17,017	$ 20,018
Fair Value
Due within one year	999
Due after one year through five years	4,327
Due after five years through ten years	3,921
Due after ten years	1,115
Mortgage and asset-backed securities	5,834
Fair Value	$ 16,196	$ 18,635