SECURITIES - Summary of Available For Sale and Held to Maturity Securities (Details) - USD ($)	Sep. 30, 2023	Dec. 31, 2022
Debt Securities, Available-for-Sale [Abstract]
Amortized Cost	$ 1,241,921,000	$ 1,400,783,000
Gross Unrealized Gain	13,000	224,000
Gross Unrealized Losses	(266,402,000)	(215,479,000)
Allowance for Credit Losses	0	0
Fair Value	975,532,000	1,185,528,000
U.S. Treasury securities
Debt Securities, Available-for-Sale [Abstract]
Amortized Cost	2,873,000	3,057,000
Gross Unrealized Gain	0	0
Gross Unrealized Losses	(12,000)	(23,000)
Allowance for Credit Losses	0	0
Fair Value	2,861,000	3,034,000
U.S. government sponsored agencies
Debt Securities, Available-for-Sale [Abstract]
Amortized Cost	148,895,000	156,184,000
Gross Unrealized Gain	0	0
Gross Unrealized Losses	(33,224,000)	(29,223,000)
Allowance for Credit Losses	0	0
Fair Value	115,671,000	126,961,000
Mortgage-backed securities: residential
Debt Securities, Available-for-Sale [Abstract]
Amortized Cost	531,807,000	578,175,000
Gross Unrealized Gain	12,000	67,000
Gross Unrealized Losses	(102,157,000)	(85,934,000)
Allowance for Credit Losses	0	0
Fair Value	429,662,000	492,308,000
State and municipal securities
Debt Securities, Available-for-Sale [Abstract]
Amortized Cost	558,346,000	663,367,000
Gross Unrealized Gain	1,000	157,000
Gross Unrealized Losses	(131,009,000)	(100,299,000)
Allowance for Credit Losses	0	0
Fair Value	$ 427,338,000	$ 563,225,000