SECURITIES - Scheduled Maturities of Securities HTM and the Related Weighted Average Yields (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
HTM - Amortized Cost
Amortized cost, one through five years	$ 3,465	$ 208
Amortized cost, five through ten years	14,411	17,689
Amortized cost, after ten years	782,866	844,647
Amortized cost, total	$ 800,742	$ 862,544
HTM - Weighted average yield
Weighted average yield, one through five years	0.84%	0.36%
Weighted average yield, five through ten years	1.36%	1.12%
Weighted average yield, after ten years	2.28%	2.31%
Weighted average yield, total	2.25%	2.28%
HTM - Estimated Fair Value
Estimated fair value, one through five years	$ 3,183	$ 192
Estimated fair value, five through ten years	12,730	16,148
Estimated fair value, after ten years	678,583	756,721
Estimated fair value, total	694,496	773,061
Agency mortgage-backed securities
HTM - Amortized Cost
Amortized cost, one through five years	3,465	208
Amortized cost, five through ten years	14,411	17,689
Amortized cost, after ten years	782,866	844,647
Amortized cost, total	800,742	862,544
HTM - Estimated Fair Value
Estimated fair value, one through five years	3,183	192
Estimated fair value, five through ten years	12,730	16,148
Estimated fair value, after ten years	678,583	756,721
Estimated fair value, total	$ 694,496	$ 773,061