INVESTMENT SECURITIES - Schedule of Gross Unrealized Losses and Fair Value of Securities (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Estimated Fair Value
Less Than 12 Months	$ 77,723	$ 162,258
12 Months or More	903,064	1,154,553
Total	980,787	1,316,811
Unrealized Losses
Less Than 12 Months	(167)	(827)
12 Months or More	(24,262)	(43,909)
Total	(24,429)	(44,736)
U.S. Treasuries
Estimated Fair Value
Less Than 12 Months	0	159,667
12 Months or More	352,918	537,313
Total	352,918	696,980
Unrealized Losses
Less Than 12 Months	0	(827)
12 Months or More	(4,067)	(10,966)
Total	(4,067)	(11,793)
U.S. government-sponsored agencies
Estimated Fair Value
Less Than 12 Months	0	0
12 Months or More	995	985
Total	995	985
Unrealized Losses
Less Than 12 Months	0	0
12 Months or More	(18)	(38)
Total	(18)	(38)
State, county and municipal securities
Estimated Fair Value
Less Than 12 Months	0	1,923
12 Months or More	17,090	19,754
Total	17,090	21,677
Unrealized Losses
Less Than 12 Months	0	0
12 Months or More	(746)	(944)
Total	(746)	(944)
Corporate debt securities
Estimated Fair Value
Less Than 12 Months	0	500
12 Months or More	8,320	8,527
Total	8,320	9,027
Unrealized Losses
Less Than 12 Months	0	0
12 Months or More	(664)	(850)
Total	(664)	(850)
SBA pool securities
Estimated Fair Value
Less Than 12 Months	55,570	42
12 Months or More	18,478	21,267
Total	74,048	21,309
Unrealized Losses
Less Than 12 Months	(117)	0
12 Months or More	(969)	(1,519)
Total	(1,086)	(1,519)
Mortgage-backed securities
Estimated Fair Value
Less Than 12 Months	22,153	126
12 Months or More	505,263	566,707
Total	527,416	566,833
Unrealized Losses
Less Than 12 Months	(50)	0
12 Months or More	(17,798)	(29,592)
Total	$ (17,848)	$ (29,592)