INVESTMENT SECURITIES - Amortized Cost and Estimated Fair Value of Investment Securities Available for Sale (Details) - USD ($) $ in Thousands	Sep. 30, 2025	Jun. 30, 2025	Dec. 31, 2024	Sep. 30, 2024	Jun. 30, 2024	Dec. 31, 2023
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 2,121,750		$ 1,708,196
Allowance for Credit Losses	(74)	$ (66)	(69)	$ (66)	$ (68)	$ (69)
Gross Unrealized Gains	25,922		2,171
Gross Unrealized Losses	(15,927)		(39,038)
Estimated Fair Value	2,131,671		1,671,260
U.S. Treasuries
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	677,981		800,860
Allowance for Credit Losses	0		0
Gross Unrealized Gains	7,471		669
Gross Unrealized Losses	(562)		(5,065)
Estimated Fair Value	684,890		796,464
U.S. government-sponsored agencies
Debt Securities, Available-for-sale [Line Items]
Amortized Cost			1,010
Allowance for Credit Losses			0
Gross Unrealized Gains			0
Gross Unrealized Losses			(16)
Estimated Fair Value			994
State, county and municipal securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	21,998		25,802
Allowance for Credit Losses	0		0
Gross Unrealized Gains	4		8
Gross Unrealized Losses	(541)		(1,070)
Estimated Fair Value	21,461		24,740
Corporate debt securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	10,945		10,946
Allowance for Credit Losses	(74)		(69)
Gross Unrealized Gains	5		0
Gross Unrealized Losses	(465)		(594)
Estimated Fair Value	10,411		10,283
SBA pool securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	13,603		72,036
Allowance for Credit Losses	0		0
Gross Unrealized Gains	0		0
Gross Unrealized Losses	(691)		(1,554)
Estimated Fair Value	12,912		70,482
Mortgage-backed securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	1,397,223		797,542
Allowance for Credit Losses	0		0
Gross Unrealized Gains	18,442		1,494
Gross Unrealized Losses	(13,668)		(30,739)
Estimated Fair Value	$ 1,401,997		$ 768,297