LOANS AND ALLOWANCE FOR CREDIT LOSSES - Summary of Balances of Loans (Details) - USD ($)	Mar. 31, 2024	Dec. 31, 2023	Mar. 31, 2023	Dec. 31, 2022
Loans
Total loans before basis adjustment	$ 4,777,221,000	$ 4,749,418,000
Basis adjustment associated with fair value hedge	(536,000)	893,000
Total loans	4,776,685,000	4,750,311,000
Allowance for credit losses on loans	(48,185,000)	(47,972,000)	$ (46,994,000)	$ (45,236,000)
Net loans	4,728,500,000	4,702,339,000
Net deferred loan costs	8,700,000	8,500,000
PPP loans | Commercial and industrial
Loans
Loans before fees	278,000	321,000
Deferred processing fee income	32,000	36,000
Residential
Loans
Total loans before basis adjustment	1,696,222,000	1,708,821,000
Total loans	1,696,222,000	1,708,821,000
Residential | 1-4 family
Loans
Total loans	1,507,959,000	1,513,554,000
Allowance for credit losses on loans	(12,035,000)	(12,101,000)	(11,508,000)	(11,532,000)
Residential | Second mortgages and equity lines of credit
Loans
Total loans	173,613,000	177,135,000
Allowance for credit losses on loans	(942,000)	(964,000)	(967,000)	(924,000)
Residential | Residential real estate construction
Loans
Total loans	14,650,000	18,132,000
Allowance for credit losses on loans	(331,000)	(418,000)	(755,000)	(280,000)
Commercial
Loans
Total loans	3,061,698,000	3,018,561,000
Commercial | Commercial real estate
Loans
Total loans before basis adjustment	2,355,672,000	2,343,675,000
Total loans	2,355,672,000	2,343,675,000
Allowance for credit losses on loans	(21,263,000)	(21,288,000)	(20,942,000)	(20,357,000)
Commercial | Commercial construction
Loans
Total loans before basis adjustment	234,811,000	208,443,000
Total loans	234,811,000	208,443,000
Allowance for credit losses on loans	(5,322,000)	(4,824,000)	(5,057,000)	(4,645,000)
Commercial | Commercial and industrial
Loans
Total loans before basis adjustment	471,215,000	466,443,000
Total loans	471,215,000	466,443,000
Allowance for credit losses on loans	(8,063,000)	(8,107,000)	(7,484,000)	(7,236,000)
Consumer loans
Loans
Total loans before basis adjustment	19,301,000	22,036,000
Total loans	19,301,000	22,036,000
Allowance for credit losses on loans	(229,000)	(270,000)	$ (281,000)	$ (262,000)
Consumer loans | Auto
Loans
Total loans	11,888,000	13,603,000
Consumer loans | Personal
Loans
Total loans	$ 7,413,000	$ 8,433,000