INVESTMENT SECURITIES - Amortized Cost and Estimated Fair Value of Investment Securities Available for Sale (Details) - USD ($) $ in Thousands	Mar. 31, 2025	Dec. 31, 2024	Mar. 31, 2024	Dec. 31, 2023
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 1,959,038	$ 1,708,196
Allowance for Credit Losses	(69)	(69)	$ (73)	$ (69)
Gross Unrealized Gains	9,826	2,171
Gross Unrealized Losses	(25,784)	(39,038)
Estimated Fair Value	1,943,011	1,671,260
U.S. Treasuries
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	926,330	800,860
Allowance for Credit Losses	0	0
Gross Unrealized Gains	5,009	669
Gross Unrealized Losses	(1,421)	(5,065)
Estimated Fair Value	929,918	796,464
U.S. government-sponsored agencies
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	1,007	1,010
Allowance for Credit Losses	0	0
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(11)	(16)
Estimated Fair Value	996	994
State, county and municipal securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	25,734	25,802
Allowance for Credit Losses	0	0
Gross Unrealized Gains	5	8
Gross Unrealized Losses	(976)	(1,070)
Estimated Fair Value	24,763	24,740
Corporate debt securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	10,946	10,946
Allowance for Credit Losses	(69)	(69)
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(435)	(594)
Estimated Fair Value	10,442	10,283
SBA pool securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	66,747	72,036
Allowance for Credit Losses	0	0
Gross Unrealized Gains	47	0
Gross Unrealized Losses	(1,084)	(1,554)
Estimated Fair Value	65,710	70,482
Mortgage-backed securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	928,274	797,542
Allowance for Credit Losses	0	0
Gross Unrealized Gains	4,765	1,494
Gross Unrealized Losses	(21,857)	(30,739)
Estimated Fair Value	$ 911,182	$ 768,297