INVESTMENT SECURITIES (Investment Securities at an Unrealized Loss Position) (Details) $ in Thousands	Sep. 30, 2023 USD ($) security	Dec. 31, 2022 USD ($) security
Investments, Debt and Equity Securities [Abstract]
Number of HTM investment securities in an unrealized loss position | security	83
Number of AFS investment securities in an unrealized loss position | security	245	243
Schedule of Held-to-Maturity Securities [Line Items]
Less Than 12 Months, Fair Value	$ 17,533	$ 596,780
Less Than 12 Months, Unrecognized Losses	(469)	(68,103)
12 Month or Longer, Fair Value	514,354	0
12 Month or Longer, Unrecognized Losses	(107,697)	0
Total Fair Value	531,887	596,780
Total Unrecognized Losses	(108,166)	(68,103)
Debt Securities, Available-for-Sale [Line Items]
Less than 12 months, Fair Value	39,665	240,949
Less Than 12 Months, Unrecognized Losses	(1,306)	(21,134)
12 Month or Longer, Fair Value	584,408	425,202
12 Month or Longer, Unrecognized Losses	(145,815)	(108,448)
Total Fair Value	624,073	666,151
Total Unrecognized Losses	147,121	129,582
States and political subdivisions
Schedule of Held-to-Maturity Securities [Line Items]
Less Than 12 Months, Fair Value	0	37,113
Less Than 12 Months, Unrecognized Losses	0	(4,727)
12 Month or Longer, Fair Value	32,038	0
12 Month or Longer, Unrecognized Losses	(9,892)	0
Total Fair Value	32,038	37,113
Total Unrecognized Losses	(9,892)	(4,727)
Debt Securities, Available-for-Sale [Line Items]
Less than 12 months, Fair Value	13,958	52,244
Less Than 12 Months, Unrecognized Losses	(393)	(4,807)
12 Month or Longer, Fair Value	111,019	78,389
12 Month or Longer, Unrecognized Losses	(39,157)	(31,874)
Total Fair Value	124,977	130,633
Total Unrecognized Losses	39,550	36,681
Corporate securities
Debt Securities, Available-for-Sale [Line Items]
Less than 12 months, Fair Value	0	0
Less Than 12 Months, Unrecognized Losses	0	0
12 Month or Longer, Fair Value	30,019	30,211
12 Month or Longer, Unrecognized Losses	(5,830)	(5,995)
Total Fair Value	30,019	30,211
Total Unrecognized Losses	5,830	5,995
Residential - U.S. Government-sponsored enterprises
Schedule of Held-to-Maturity Securities [Line Items]
Less Than 12 Months, Fair Value	17,533	559,667
Less Than 12 Months, Unrecognized Losses	(469)	(63,376)
12 Month or Longer, Fair Value	482,316	0
12 Month or Longer, Unrecognized Losses	(97,805)	0
Total Fair Value	499,849	559,667
Total Unrecognized Losses	(98,274)	(63,376)
Debt Securities, Available-for-Sale [Line Items]
Less than 12 months, Fair Value	0	149,624
Less Than 12 Months, Unrecognized Losses	0	(13,990)
12 Month or Longer, Fair Value	378,873	274,179
12 Month or Longer, Unrecognized Losses	(88,428)	(61,196)
Total Fair Value	378,873	423,803
Total Unrecognized Losses	88,428	75,186
U.S. Treasury obligations and direct obligations of U.S. Government agencies
Debt Securities, Available-for-Sale [Line Items]
Less than 12 months, Fair Value	4,236	9,651
Less Than 12 Months, Unrecognized Losses	(110)	(245)
12 Month or Longer, Fair Value	16,076	15,541
12 Month or Longer, Unrecognized Losses	(2,215)	(2,072)
Total Fair Value	20,312	25,192
Total Unrecognized Losses	2,325	2,317
Residential - Non-government agencies
Debt Securities, Available-for-Sale [Line Items]
Less than 12 months, Fair Value	6,706	2,890
Less Than 12 Months, Unrecognized Losses	(487)	(334)
12 Month or Longer, Fair Value	5,373	5,772
12 Month or Longer, Unrecognized Losses	(970)	(833)
Total Fair Value	12,079	8,662
Total Unrecognized Losses	1,457	1,167
Commercial - U.S. Government-sponsored enterprises
Debt Securities, Available-for-Sale [Line Items]
Less than 12 months, Fair Value	0	25,034
Less Than 12 Months, Unrecognized Losses	0	(1,724)
12 Month or Longer, Fair Value	43,048	21,110
12 Month or Longer, Unrecognized Losses	(9,215)	(6,478)
Total Fair Value	43,048	46,144
Total Unrecognized Losses	9,215	8,202
Commercial - Non-government agencies
Debt Securities, Available-for-Sale [Line Items]
Less than 12 months, Fair Value	14,765	1,506
Less Than 12 Months, Unrecognized Losses	(316)	(34)
12 Month or Longer, Fair Value	0	0
12 Month or Longer, Unrecognized Losses	0	0
Total Fair Value	14,765	1,506
Total Unrecognized Losses	$ 316	$ 34