INVESTMENT SECURITIES - Amortized Cost and Fair Value of Available for Sale Securities and Held to Maturity Securities by Contractual Maturity (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Amortized Cost
Due in one year or less	$ 1,865	$ 1,390
Due after one through five years	24,392	24,899
Due after five through ten years	141,962	127,948
Due after ten years	1,134,476	1,151,260
Total debt securities with a single maturity date	1,302,695	1,305,497
Total investment securities	1,867,872	1,846,840
Fair Value
Due in one year or less	1,855	1,382
Due after one through five years	22,654	23,372
Due after five through ten years	131,832	120,385
Due after ten years	991,828	1,027,158
Total debt securities with a single maturity date	1,148,169	1,172,297
Total investment securities	1,620,213	1,627,112
Amortized Cost
Due in one year or less	12,971	3,041
Due after one through five years	112,676	118,592
Due after five through ten years	137,043	135,805
Due after ten years	1,206,968	1,217,265
Total debt securities with a single maturity date	1,469,658	1,474,703
Total investment securities	2,163,606	2,184,497
Fair Value
Due in one year or less	12,831	3,043
Due after one through five years	105,283	111,723
Due after five through ten years	125,783	126,461
Due after ten years	988,923	1,018,801
Total debt securities with a single maturity date	1,232,820	1,260,028
Total investment securities	1,820,451	1,870,374
U.S. Government-sponsored mortgage-backed securities
Amortized Cost
U.S. Government-sponsored mortgage-backed securities	565,177	541,343
Fair Value
U.S. Government-sponsored mortgage-backed securities	472,044	454,815
Total investment securities	472,044	454,815
Amortized Cost
U.S. Government-sponsored mortgage-backed securities	693,948	709,794
Total investment securities	693,948	709,794
Fair Value
U.S. Government-sponsored mortgage-backed securities	587,631	610,346
Total investment securities	$ 587,631	$ 610,346