INVESTMENT SECURITIES - Schedule of Gross Unrealized Losses and Fair Value of Securities (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Estimated Fair Value
Less than 12 months, estimated fair value	$ 891,875	$ 1,405,288
12 months or more, estimated fair value	385,315	27,331
Total estimated fair value	1,277,190	1,432,619
Unrealized Losses
Less than 12 months, unrealized losses	(24,010)	(56,816)
12 months or more, unrealized losses	(21,466)	(2,318)
Total unrealized losses	(45,476)	(59,134)
U.S. Treasuries
Estimated Fair Value
Less than 12 months, estimated fair value	509,696	725,250
12 months or more, estimated fair value	73,070	0
Total estimated fair value	582,766	725,250
Unrealized Losses
Less than 12 months, unrealized losses	(9,501)	(16,381)
12 months or more, unrealized losses	(1,864)	0
Total unrealized losses	(11,365)	(16,381)
U.S. government-sponsored agencies
Estimated Fair Value
Less than 12 months, estimated fair value	0	979
12 months or more, estimated fair value	987	0
Total estimated fair value	987	979
Unrealized Losses
Less than 12 months, unrealized losses	0	(57)
12 months or more, unrealized losses	(45)	0
Total unrealized losses	(45)	(57)
State, county and municipal securities
Estimated Fair Value
Less than 12 months, estimated fair value	11,374	27,438
12 months or more, estimated fair value	12,223	0
Total estimated fair value	23,597	27,438
Unrealized Losses
Less than 12 months, unrealized losses	(174)	(1,180)
12 months or more, unrealized losses	(599)	0
Total unrealized losses	(773)	(1,180)
Corporate debt securities
Estimated Fair Value
Less than 12 months, estimated fair value	888	13,271
12 months or more, estimated fair value	13,223	1,155
Total estimated fair value	14,111	14,426
Unrealized Losses
Less than 12 months, unrealized losses	(10)	(126)
12 months or more, unrealized losses	(695)	(270)
Total unrealized losses	(705)	(396)
SBA pool securities
Estimated Fair Value
Less than 12 months, estimated fair value	472	17,806
12 months or more, estimated fair value	24,660	9,329
Total estimated fair value	25,132	27,135
Unrealized Losses
Less than 12 months, unrealized losses	(20)	(1,298)
12 months or more, unrealized losses	(1,583)	(729)
Total unrealized losses	(1,603)	(2,027)
Mortgage-backed securities
Estimated Fair Value
Less than 12 months, estimated fair value	369,445	620,544
12 months or more, estimated fair value	261,152	16,847
Total estimated fair value	630,597	637,391
Unrealized Losses
Less than 12 months, unrealized losses	(14,305)	(37,774)
12 months or more, unrealized losses	(16,680)	(1,319)
Total unrealized losses	$ (30,985)	$ (39,093)