SECURITIES - Securities in a Continuous Unrealized Loss Position (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Debt Securities, Available-for-sale [Line Items]
Securities in a Continuous Unrealized Loss Position, Less than 12 months, Estimated Fair Value	$ 368,333	$ 225,879
Securities in a Continuous Unrealized Loss Position, Less than 12 Months, Unrealized Losses	(6,866)	(5,739)
Securities in a Continuous Unrealized Loss Position, More than 12 Months, Estimated Fair Value	1,083,379	1,024,020
Securities in a Continuous Unrealized Loss Position, More than 12 Months Unrealized Losses	(147,967)	(146,014)
Securities in a Continuous Unrealized Loss Position, Total Estimated Fair Value	1,451,712	1,249,899
Securities in a Continuous Unrealized Loss Position, Total Unrealized Losses	(154,833)	(151,753)
U.S. government and agency securities
Debt Securities, Available-for-sale [Line Items]
Securities in a Continuous Unrealized Loss Position, Less than 12 months, Estimated Fair Value	23,505	110,038
Securities in a Continuous Unrealized Loss Position, Less than 12 Months, Unrealized Losses	(233)	(2,208)
Securities in a Continuous Unrealized Loss Position, More than 12 Months, Estimated Fair Value	217,429	154,145
Securities in a Continuous Unrealized Loss Position, More than 12 Months Unrealized Losses	(8,212)	(7,993)
Securities in a Continuous Unrealized Loss Position, Total Estimated Fair Value	240,934	264,183
Securities in a Continuous Unrealized Loss Position, Total Unrealized Losses	(8,445)	(10,201)
Municipal securities
Debt Securities, Available-for-sale [Line Items]
Securities in a Continuous Unrealized Loss Position, Less than 12 months, Estimated Fair Value	5,249	1,303
Securities in a Continuous Unrealized Loss Position, Less than 12 Months, Unrealized Losses	(111)	(14)
Securities in a Continuous Unrealized Loss Position, More than 12 Months, Estimated Fair Value	170,568	177,957
Securities in a Continuous Unrealized Loss Position, More than 12 Months Unrealized Losses	(26,667)	(27,157)
Securities in a Continuous Unrealized Loss Position, Total Estimated Fair Value	175,817	179,260
Securities in a Continuous Unrealized Loss Position, Total Unrealized Losses	(26,778)	(27,171)
Agency mortgage-backed pass-through securities
Debt Securities, Available-for-sale [Line Items]
Securities in a Continuous Unrealized Loss Position, Less than 12 months, Estimated Fair Value	109,961	80,208
Securities in a Continuous Unrealized Loss Position, Less than 12 Months, Unrealized Losses	(1,868)	(1,444)
Securities in a Continuous Unrealized Loss Position, More than 12 Months, Estimated Fair Value	291,919	257,779
Securities in a Continuous Unrealized Loss Position, More than 12 Months Unrealized Losses	(38,311)	(35,717)
Securities in a Continuous Unrealized Loss Position, Total Estimated Fair Value	401,880	337,987
Securities in a Continuous Unrealized Loss Position, Total Unrealized Losses	(40,179)	(37,161)
Agency collateralized mortgage obligations
Debt Securities, Available-for-sale [Line Items]
Securities in a Continuous Unrealized Loss Position, Less than 12 months, Estimated Fair Value	222,596	23,051
Securities in a Continuous Unrealized Loss Position, Less than 12 Months, Unrealized Losses	(2,072)	(621)
Securities in a Continuous Unrealized Loss Position, More than 12 Months, Estimated Fair Value	323,436	348,854
Securities in a Continuous Unrealized Loss Position, More than 12 Months Unrealized Losses	(64,927)	(63,932)
Securities in a Continuous Unrealized Loss Position, Total Estimated Fair Value	546,032	371,905
Securities in a Continuous Unrealized Loss Position, Total Unrealized Losses	(66,999)	(64,553)
Corporate bonds and other
Debt Securities, Available-for-sale [Line Items]
Securities in a Continuous Unrealized Loss Position, Less than 12 months, Estimated Fair Value	7,022	11,279
Securities in a Continuous Unrealized Loss Position, Less than 12 Months, Unrealized Losses	(2,582)	(1,452)
Securities in a Continuous Unrealized Loss Position, More than 12 Months, Estimated Fair Value	80,027	85,285
Securities in a Continuous Unrealized Loss Position, More than 12 Months Unrealized Losses	(9,850)	(11,215)
Securities in a Continuous Unrealized Loss Position, Total Estimated Fair Value	87,049	96,564
Securities in a Continuous Unrealized Loss Position, Total Unrealized Losses	$ (12,432)	$ (12,667)