INVESTMENT SECURITIES - Schedule of Amortized Cost and Estimated Fair Value of Investment Securities Available for Sale (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 1,447,637	$ 1,559,005
Allowance for Credit Losses	(69)	(75)	$ 0	$ (112)
Gross Unrealized Gains	112	264
Gross Unrealized Losses	(44,736)	(59,134)
Estimated Fair Value	1,402,944	1,500,060
U.S. Treasuries
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	732,636	775,784
Allowance for Credit Losses	0	0
Gross Unrealized Gains	34	131
Gross Unrealized Losses	(11,793)	(16,381)
Estimated Fair Value	720,877	759,534
U.S. government-sponsored agencies
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	1,023	1,036
Allowance for Credit Losses	0	0
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(38)	(57)
Estimated Fair Value	985	979
State, county and municipal securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	28,986	35,358
Allowance for Credit Losses	0	0
Gross Unrealized Gains	9	17
Gross Unrealized Losses	(944)	(1,180)
Estimated Fair Value	28,051	34,195
Corporate debt securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	10,946	16,397
Allowance for Credit Losses	(69)	(75)
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(850)	(396)
Estimated Fair Value	10,027	15,926
SBA pool securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	53,033	29,422
Allowance for Credit Losses	0	0
Gross Unrealized Gains	2	3
Gross Unrealized Losses	(1,519)	(2,027)
Estimated Fair Value	51,516	27,398
Mortgage-backed securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	621,013	701,008
Allowance for Credit Losses	0	0
Gross Unrealized Gains	67	113
Gross Unrealized Losses	(29,592)	(39,093)
Estimated Fair Value	$ 591,488	$ 662,028