INVESTMENT SECURITIES - Unrealized Gain (Loss) on Investments (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
AVAILABLE-FOR-SALE SECURITIES:
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	$ 312,805	$ 147,033
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	11,669	2,019
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	38,737	26,881
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	4,333	1,266
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	351,542	173,914
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	16,002	3,285
Allowance for credit losses on securities	0
HELD-TO-MATURITY SECURITIES:
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	4,492
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	151,979
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	2,761
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	68,209
Debt Securities, Held-to-maturity, Unrealized Loss Position, Fair Value	220,188
Debt Securities, Held-to-maturity, Unrealized Loss Position, Accumulated Loss	7,253
Agency mortgage-backed securities
AVAILABLE-FOR-SALE SECURITIES:
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	244,661	47,769
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	9,337	388
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		10,583
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss		356
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	244,661	58,352
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	9,337	744
HELD-TO-MATURITY SECURITIES:
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	2,662
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	80,283
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	304
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	9,717
Debt Securities, Held-to-maturity, Unrealized Loss Position, Fair Value	90,000
Debt Securities, Held-to-maturity, Unrealized Loss Position, Accumulated Loss	2,966
Agency collateralized mortgage obligations
AVAILABLE-FOR-SALE SECURITIES:
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	25,813	92,727
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	1,177	1,588
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	34,761	16,298
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	4,086	910
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	60,574	109,025
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	5,263	2,498
HELD-TO-MATURITY SECURITIES:
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	1,772
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	70,764
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	2,251
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	53,431
Debt Securities, Held-to-maturity, Unrealized Loss Position, Fair Value	124,195
Debt Securities, Held-to-maturity, Unrealized Loss Position, Accumulated Loss	4,023
States and political subdivisions securities
AVAILABLE-FOR-SALE SECURITIES:
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	17,527	6,537
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	179	43
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	3,976
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	247
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	21,503	6,537
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	426	$ 43
HELD-TO-MATURITY SECURITIES:
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	58
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	932
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	206
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	5,061
Debt Securities, Held-to-maturity, Unrealized Loss Position, Fair Value	5,993
Debt Securities, Held-to-maturity, Unrealized Loss Position, Accumulated Loss	264
Small Business Administration securities
AVAILABLE-FOR-SALE SECURITIES:
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	24,804
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	976
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	24,804
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	$ 976

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Amount of allowance for credit loss 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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