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LOANS AND ALLOWANCE FOR CREDIT LOSSES - Summary of Total Loans (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2026	Dec. 31, 2025	Jun. 30, 2026	Sep. 30, 2025	Jun. 30, 2025	Dec. 31, 2024
LOANS AND ALLOWANCE FOR CREDIT LOSSES
Total loans	$ 3,613,632	$ 3,605,859
Allowance for credit losses	31,761	34,052	$ 32,231	$ 33,940	$ 28,885	$ 28,744
Net loans	3,581,871	3,571,807
Accrued interest receivable for loans	12,100	11,500
Municipal and other
LOANS AND ALLOWANCE FOR CREDIT LOSSES
Total loans	42,776	43,106
Allowance for credit losses	93	119	95	128	110	128
Home equity
LOANS AND ALLOWANCE FOR CREDIT LOSSES
Total loans	121,650	114,484
Allowance for credit losses	827	814	778	919	786	741
Total commercial loans \| Commercial construction
LOANS AND ALLOWANCE FOR CREDIT LOSSES
Total loans	244,237	213,779
Allowance for credit losses	4,906	4,371	4,877	2,522	2,032	2,096
Total commercial real estate \| Commercial real estate owner occupied
LOANS AND ALLOWANCE FOR CREDIT LOSSES
Total loans	354,794	385,843
Allowance for credit losses	3,481	4,045	3,459	3,191	2,823	2,794
Total commercial real estate \| Commercial real estate non-owner occupied
LOANS AND ALLOWANCE FOR CREDIT LOSSES
Total loans	1,472,297	1,450,597
Allowance for credit losses	11,679	12,837	11,512	12,699	10,980	11,104
Total commercial and industrial \| Commercial and industrial
LOANS AND ALLOWANCE FOR CREDIT LOSSES
Total loans	330,758	315,370
Allowance for credit losses	4,791	5,378	5,729	6,285	5,664	5,064
Total residential real estate \| Residential real estate
LOANS AND ALLOWANCE FOR CREDIT LOSSES
Total loans	1,032,975	1,068,413
Allowance for credit losses	5,778	6,350	5,640	8,024	6,406	6,732
Total consumer \| Consumer other
LOANS AND ALLOWANCE FOR CREDIT LOSSES
Total loans	14,145	14,267
Allowance for credit losses	$ 206	$ 138	$ 141	$ 172	$ 84	$ 85