INVESTMENT SECURITIES - Available-for-Sale Securities (Details) (Details) - USD ($) $ in Thousands	Dec. 31, 2025	Dec. 31, 2024
Amortized Cost
Available-for-sale, amortized cost	$ 13,813,551	$ 11,940,774
Fair  Value
Total fair value	13,580,285	11,467,560
Investment securities
Amortized Cost
Due within one year	1,494,158
Due after one year through five years	6,668,349
Due after five years through ten years	3,451,994
Due after ten years	2,199,050
Available-for-sale, amortized cost	13,813,551	11,940,774
Fair  Value
Due within one year	1,488,988
Due after one year through five years	6,659,089
Due after five years through ten years	3,324,384
Due after ten years	2,107,824
Total fair value	$ 13,580,285	11,467,560
Weighted-Average Yield
Due within one year	3.46%
Due after one year through five years	4.07%
Due after five years through ten years	3.59%
Due after ten years	4.26%
Weighted-average yield	3.93%
Available-for-sale, accrued interest excluded	$ 91,300	$ 79,700