INVESTMENT SECURITIES - Amortized Cost and Fair Value of Available for Sale Securities and Held to Maturity Securities by Contractual Maturity (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Amortized Cost
Due in one year or less	$ 1,809	$ 1,390
Due after one through five years	12,818	24,899
Due after five through ten years	162,996	127,948
Due after ten years	1,023,957	1,151,260
Total debt securities with a single maturity date	1,201,580	1,305,497
Total investment securities	1,742,679	1,846,840
Fair Value
Due in one year or less	1,800	1,382
Due after one through five years	12,578	23,372
Due after five through ten years	151,369	120,385
Due after ten years	915,703	1,027,158
Total debt securities with a single maturity date	1,081,450	1,172,297
Total investment securities	1,553,496	1,627,112
Amortized Cost
Due in one year or less	15,139	3,041
Due after one through five years	121,204	118,592
Due after five through ten years	165,418	135,805
Due after ten years	1,149,054	1,217,265
Total debt securities with a single maturity date	1,450,815	1,474,703
Total investment securities	2,108,894	2,184,497
Fair Value
Due in one year or less	15,096	3,043
Due after one through five years	116,480	111,723
Due after five through ten years	151,803	126,461
Due after ten years	963,930	1,018,801
Total debt securities with a single maturity date	1,247,309	1,260,028
Total investment securities	1,823,006	1,870,374
U.S. Government-sponsored mortgage-backed securities
Amortized Cost
U.S. Government-sponsored mortgage-backed securities	541,099	541,343
Fair Value
U.S. Government-sponsored mortgage-backed securities	472,046	454,815
Total investment securities	472,046	454,815
Amortized Cost
U.S. Government-sponsored mortgage-backed securities	658,079	709,794
Total investment securities	658,079	709,794
Fair Value
U.S. Government-sponsored mortgage-backed securities	575,697	610,346
Total investment securities	$ 575,697	$ 610,346