INVESTMENTS (Schedule of Unrealized Gross Losses and Estimated Fair values of Investment Securities) (Details) $ in Thousands	Sep. 30, 2021 USD ($) security	Dec. 31, 2020 USD ($) security
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Unrealized Loss Position, Number of Positions \| security	138	30
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	$ 727,811	$ 107,635
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	9,191	916
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	30,128	980
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(753)	(6)
Debt Securities, Available-for-sale, Unrealized Loss Position, Total	757,939	108,615
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ 9,944	$ 922
Obligations of states and political subdivisions
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Unrealized Loss Position, Number of Positions \| security	3	1
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	$ 2,554	$ 2,404
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	6	115
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	2,322	0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(196)	0
Debt Securities, Available-for-sale, Unrealized Loss Position, Total	4,876	2,404
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ 202	$ 115
Mortgage-backed securities issued or guaranteed by U.S. government-sponsored enterprises
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Unrealized Loss Position, Number of Positions \| security	83	15
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	$ 528,776	$ 61,222
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	6,286	568
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	14,565	980
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(325)	(6)
Debt Securities, Available-for-sale, Unrealized Loss Position, Total	543,341	62,202
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ 6,611	$ 574
Collateralized mortgage obligations issued or guaranteed by U.S. government-sponsored enterprises
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Unrealized Loss Position, Number of Positions \| security	44	9
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	$ 180,559	$ 39,107
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	2,664	135
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	13,241	0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(232)	0
Debt Securities, Available-for-sale, Unrealized Loss Position, Total	193,800	39,107
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ 2,896	$ 135
Subordinated corporate bonds
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Unrealized Loss Position, Number of Positions \| security	5	5
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	$ 8,471	$ 4,902
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	101	98
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	0	0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	0	0
Debt Securities, Available-for-sale, Unrealized Loss Position, Total	8,471	4,902
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ 101	$ 98
Obligations of U.S. government-sponsored enterprises
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Unrealized Loss Position, Number of Positions \| security	3
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	$ 7,451
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	134
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	0
Debt Securities, Available-for-sale, Unrealized Loss Position, Total	7,451
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ 134

Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for more than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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