SECURITIES (Debt securities available for sale) (Details) $ in Thousands	Sep. 30, 2024 USD ($) security investmentCategory	Dec. 31, 2023 USD ($) security
Fair Value
Less than 12 months	$ 101,267	$ 629,647
12 months or longer	3,278,546	3,770,658
Total	3,379,813	4,400,305
Unrealized Losses
Less than 12 months	(12,206)	(34,481)
12 months or longer	(330,964)	(419,373)
Total	$ (343,170)	$ (453,854)
Count
Less than 12 months | security	8	21
12 months or longer | security	376	406
Total | security	384	427
Number of investment categories | investmentCategory	2
U.S. treasuries
Fair Value
Less than 12 months	$ 0	$ 2,985
12 months or longer	4,955	26,138
Total	4,955	29,123
Unrealized Losses
Less than 12 months	0	(12)
12 months or longer	(48)	(329)
Total	$ (48)	$ (341)
Count
Less than 12 months | security	0	1
12 months or longer | security	1	3
Total | security	1	4
U.S. agencies
Fair Value
Less than 12 months	$ 0	$ 0
12 months or longer	11,440	14,530
Total	11,440	14,530
Unrealized Losses
Less than 12 months	0	0
12 months or longer	(100)	(194)
Total	$ (100)	$ (194)
Count
Less than 12 months | security	0	0
12 months or longer | security	4	4
Total | security	4	4
Obligations of states and political subdivisions
Fair Value
Less than 12 months	$ 1,690	$ 1,440
12 months or longer	732,155	736,653
Total	733,845	738,093
Unrealized Losses
Less than 12 months	(10)	(65)
12 months or longer	(91,100)	(98,469)
Total	$ (91,110)	$ (98,534)
Count
Less than 12 months | security	3	1
12 months or longer | security	146	150
Total | security	149	151
Mortgage-backed securities - agency
Fair Value
Less than 12 months	$ 0	$ 194
12 months or longer	1,338,682	1,392,769
Total	1,338,682	1,392,963
Unrealized Losses
Less than 12 months	0	(2)
12 months or longer	(184,934)	(226,791)
Total	$ (184,934)	$ (226,793)
Count
Less than 12 months | security	0	2
12 months or longer | security	158	166
Total | security	158	168
Mortgage-backed securities - non-agency
Fair Value
Less than 12 months	$ 738	$ 415,934
12 months or longer	666,901	902,291
Total	667,639	1,318,225
Unrealized Losses
Less than 12 months	(7,756)	(24,568)
12 months or longer	(34,570)	(63,081)
Total	$ (42,326)	$ (87,649)
Count
Less than 12 months | security	1	12
12 months or longer | security	29	35
Total | security	30	47
Commercial mortgage-backed securities - agency
Fair Value
Less than 12 months	$ 0	$ 0
12 months or longer	62,533	64,788
Total	62,533	64,788
Unrealized Losses
Less than 12 months	0	0
12 months or longer	(8,971)	(11,288)
Total	$ (8,971)	$ (11,288)
Count
Less than 12 months | security	0	0
12 months or longer | security	15	17
Total | security	15	17
Commercial mortgage-backed securities - non-agency
Fair Value
Less than 12 months	$ 7,708	$ 0
12 months or longer	375,513	507,044
Total	383,221	507,044
Unrealized Losses
Less than 12 months	(106)	0
12 months or longer	(6,279)	(12,116)
Total	$ (6,385)	$ (12,116)
Count
Less than 12 months | security	1	0
12 months or longer | security	13	16
Total | security	14	16
Asset-backed securities
Fair Value
Less than 12 months	$ 91,131	$ 148,063
12 months or longer	31,599	69,307
Total	122,730	217,370
Unrealized Losses
Less than 12 months	(4,334)	(9,723)
12 months or longer	(2,832)	(5,047)
Total	$ (7,166)	$ (14,770)
Count
Less than 12 months | security	3	4
12 months or longer | security	4	7
Total | security	7	11
Corporate bonds
Fair Value
Less than 12 months	$ 0	$ 61,031
12 months or longer	54,768	57,138
Total	54,768	118,169
Unrealized Losses
Less than 12 months	0	(111)
12 months or longer	(2,130)	(2,058)
Total	$ (2,130)	$ (2,169)
Count
Less than 12 months | security	0	1
12 months or longer | security	6	8
Total | security	6	9