SECURITIES (Available-for-sale Securities) (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Debt Securities, Available-for-sale [Line Items]
Amortized cost of securities	$ 5,100,344	$ 6,788,729
Gross Unrealized Gains	401	1,495
Gross Unrealized Losses	(453,854)	(643,080)
Debt Securities, Available-for-Sale, Excluding Accrued Interest	906,062
Equity securities with a readily determinable fair value	21,056	20,314
Estimated Fair Value	4,646,891	6,147,144
U.S. treasuries
Debt Securities, Available-for-sale [Line Items]
Total debt securities	32,459	32,369
Gross Unrealized Gains	0	8
Gross Unrealized Losses	(341)	(678)
Debt Securities, Available-for-Sale, Excluding Accrued Interest	32,118	31,699
U.S. agencies
Debt Securities, Available-for-sale [Line Items]
Total debt securities	14,724	49,437
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(194)	(6,302)
Debt Securities, Available-for-Sale, Excluding Accrued Interest	14,530	43,135
Obligations of states and political subdivisions
Debt Securities, Available-for-sale [Line Items]
Total debt securities	839,754	1,049,578
Gross Unrealized Gains	25	14
Gross Unrealized Losses	(98,534)	(170,155)
Debt Securities, Available-for-Sale, Excluding Accrued Interest	741,245	879,437
Mortgage-backed securities - agency
Debt Securities, Available-for-sale [Line Items]
Total debt securities	1,620,409	2,042,092
Gross Unrealized Gains	13	56
Gross Unrealized Losses	(226,793)	(270,043)
Debt Securities, Available-for-Sale, Excluding Accrued Interest	1,393,629	1,772,105
Mortgage-backed securities - non-agency
Debt Securities, Available-for-sale [Line Items]
Total debt securities	1,616,414	2,327,308
Gross Unrealized Gains	363	1,417
Gross Unrealized Losses	(87,649)	(146,849)
Debt Securities, Available-for-Sale, Excluding Accrued Interest	1,529,128	2,181,876
Commercial mortgage-backed securities - agency
Debt Securities, Available-for-sale [Line Items]
Total debt securities	76,076	100,518
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(11,288)	(15,395)
Debt Securities, Available-for-Sale, Excluding Accrued Interest	64,788	85,123
Commercial mortgage-backed securities - non-agency
Debt Securities, Available-for-sale [Line Items]
Total debt securities	526,974	679,511
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(12,116)	(20,052)
Debt Securities, Available-for-Sale, Excluding Accrued Interest	514,858	659,459
Asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Total debt securities	232,140	428,397
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(14,770)	(12,343)
Debt Securities, Available-for-Sale, Excluding Accrued Interest	217,370	416,054
Corporate bonds
Debt Securities, Available-for-sale [Line Items]
Total debt securities	120,338	59,205
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(2,169)	(1,263)
Debt Securities, Available-for-Sale, Excluding Accrued Interest	118,169	57,942
Total debt securities
Debt Securities, Available-for-sale [Line Items]
Total debt securities	5,079,288	6,768,415
Gross Unrealized Gains	401	1,495
Gross Unrealized Losses	(453,854)	(643,080)
Debt Securities, Available-for-Sale, Excluding Accrued Interest	$ 4,625,835	$ 6,126,830

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Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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