INVESTMENT SECURITIES - Schedule of HTM Securities Maturities (Details) - Total AFS Investment Securities - USD ($) $ in Thousands	Sep. 30, 2026	Dec. 31, 2025
Amortized Cost
Due within one year	$ 349,598
Due after one year through five years	889,752
Due after five years through ten years	505,611
Due after ten years	2,731,007
Total	4,475,968
Fair Value
Due within one year	356,248
Due after one year through five years	870,888
Due after five years through ten years	451,296
Due after ten years	2,493,175
Total	$ 4,171,607	$ 3,793,952
Weighted- Average Yield
Due within one year	3.87%
Due after one year through five years	4.27%
Due after five years through ten years	3.96%
Due after ten years	4.34%
Total, weighted-average yield	4.25%
Held-to-maturity, accrued interest excluded	$ 53,500	$ 56,700