INVESTMENT SECURITIES - Amortized Cost and Fair Value of Available for Sale Securities by Contractual Maturity (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Amortized Cost
Due in one year or less	$ 95,908
Due from one year to five years	724,844
Due from five to ten years	12,849
Due after ten years	21,846
Mortgage-backed securities	669,371
Amortized Cost	1,524,818	$ 1,559,005
Estimated Fair Value
Due in one year or less	94,723
Due from one year to five years	704,037
Due from five to ten years	12,129
Due after ten years	19,858
Mortgage-backed securities	629,609
Estimated Fair Value	1,460,356	1,500,060
Amortized Cost
Due in one year or less	0
Due from one year to five years	0
Due from five to ten years	0
Due after ten years	31,905
Mortgage-backed securities	110,608
Amortized Cost	142,513	134,864
Estimated Fair Value
Due in one year or less	0
Due from one year to five years	0
Due from five to ten years	0
Due after ten years	26,608
Mortgage-backed securities	95,283
Estimated Fair Value	$ 121,891	$ 114,538