INVESTMENT SECURITIES - Unrealized Gain (Loss) on Investments (Details) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
AVAILABLE-FOR-SALE SECURITIES:
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	$ 483,312	$ 147,033
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	34,341	2,019
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	10,479	26,881
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	2,602	1,266
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	493,791	173,914
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	36,943	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	13,781
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	181,344
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	2,320
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	17,909
Debt Securities, Held-to-maturity, Unrealized Loss Position, Fair Value	199,253
Debt Securities, Held-to-maturity, Unrealized Loss Position, Accumulated Loss	16,101
Agency mortgage-backed securities
AVAILABLE-FOR-SALE SECURITIES:
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	303,739	47,769
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	24,000	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	303,739	58,352
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	24,000	744
HELD-TO-MATURITY SECURITIES:
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	4,925
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	69,001
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	1,551
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	8,437
Debt Securities, Held-to-maturity, Unrealized Loss Position, Fair Value	77,438
Debt Securities, Held-to-maturity, Unrealized Loss Position, Accumulated Loss	6,476
Agency collateralized mortgage obligations
AVAILABLE-FOR-SALE SECURITIES:
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	64,794	92,727
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	5,116	1,588
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	10,479	16,298
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	2,602	910
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	75,273	109,025
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	7,718	2,498
HELD-TO-MATURITY SECURITIES:
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	8,439
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	109,116
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	477
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	7,161
Debt Securities, Held-to-maturity, Unrealized Loss Position, Fair Value	116,277
Debt Securities, Held-to-maturity, Unrealized Loss Position, Accumulated Loss	8,916
States and political subdivisions securities
AVAILABLE-FOR-SALE SECURITIES:
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	48,137	6,537
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	2,337	43
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	48,137	6,537
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	2,337	$ 43
HELD-TO-MATURITY SECURITIES:
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	417
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	3,227
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	292
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	2,311
Debt Securities, Held-to-maturity, Unrealized Loss Position, Fair Value	5,538
Debt Securities, Held-to-maturity, Unrealized Loss Position, Accumulated Loss	709
Small Business Administration securities
AVAILABLE-FOR-SALE SECURITIES:
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	66,642
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	2,888
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	66,642
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	$ 2,888