SECURITIES (Securities available for sale) (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Debt Securities, Available-for-sale [Line Items]
Gross Unrealized Gains	$ 95	$ 1,495
Gross Unrealized Losses	(617,642)	(643,080)
Estimated Fair Value	980,365
Equity securities with a readily determinable fair value	20,688	20,314
Amortized Cost	6,415,588	6,788,729
Estimated Fair Value	5,798,041	6,147,144
Total debt securities
Debt Securities, Available-for-sale [Line Items]
Total debt securities	6,394,900	6,768,415
Gross Unrealized Gains	95	1,495
Gross Unrealized Losses	(617,642)	(643,080)
Estimated Fair Value	5,777,353	6,126,830
U.S. treasuries
Debt Securities, Available-for-sale [Line Items]
Total debt securities	32,413	32,369
Gross Unrealized Gains	0	8
Gross Unrealized Losses	(734)	(678)
Estimated Fair Value	31,679	31,699
U.S. agencies
Debt Securities, Available-for-sale [Line Items]
Total debt securities	48,944	49,437
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(5,908)	(6,302)
Estimated Fair Value	43,036	43,135
Obligations of states and political subdivisions
Debt Securities, Available-for-sale [Line Items]
Total debt securities	985,387	1,049,578
Gross Unrealized Gains	5	14
Gross Unrealized Losses	(136,153)	(170,155)
Estimated Fair Value	849,239	879,437
Mortgage-backed securities - agency
Debt Securities, Available-for-sale [Line Items]
Total debt securities	1,958,157	2,042,092
Gross Unrealized Gains	51	56
Gross Unrealized Losses	(271,562)	(270,043)
Estimated Fair Value	1,686,646	1,772,105
Mortgage-backed securities - non-agency
Debt Securities, Available-for-sale [Line Items]
Total debt securities	2,150,547	2,327,308
Gross Unrealized Gains	39	1,417
Gross Unrealized Losses	(154,777)	(146,849)
Estimated Fair Value	1,995,809	2,181,876
Commercial mortgage-backed securities - agency
Debt Securities, Available-for-sale [Line Items]
Total debt securities	99,072	100,518
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(15,247)	(15,395)
Estimated Fair Value	83,825	85,123
Commercial mortgage-backed securities - non-agency
Debt Securities, Available-for-sale [Line Items]
Total debt securities	635,549	679,511
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(17,557)	(20,052)
Estimated Fair Value	617,992	659,459
Asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Total debt securities	425,632	428,397
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(12,916)	(12,343)
Estimated Fair Value	412,716	416,054
Corporate bonds
Debt Securities, Available-for-sale [Line Items]
Total debt securities	59,199	59,205
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(2,788)	(1,263)
Estimated Fair Value	$ 56,411	$ 57,942

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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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