LOANS AND ALLOWANCE FOR LOAN LOSSES (Credit Risk Exposure Indicators by Portfolio Segment) (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018	Jun. 30, 2018
Financing Receivable, Recorded Investment [Line Items]
Loans	$ 3,100,324	$ 3,026,222	$ 2,867,529
Pass (Grades 1-6)
Financing Receivable, Recorded Investment [Line Items]
Loans	2,706,023	2,636,966
Performing
Financing Receivable, Recorded Investment [Line Items]
Loans	344,150	346,512
Special Mention (Grade 7)
Financing Receivable, Recorded Investment [Line Items]
Loans	17,703	12,619
Substandard (Grade 8)
Financing Receivable, Recorded Investment [Line Items]
Loans	29,397	28,250
Non-performing
Financing Receivable, Recorded Investment [Line Items]
Loans	3,051	1,875
Residential Real Estate
Financing Receivable, Recorded Investment [Line Items]
Loans	1,035,792	992,866	907,910
Residential Real Estate | Pass (Grades 1-6)
Financing Receivable, Recorded Investment [Line Items]
Loans	1,026,460	983,086
Residential Real Estate | Special Mention (Grade 7)
Financing Receivable, Recorded Investment [Line Items]
Loans	482	887
Residential Real Estate | Substandard (Grade 8)
Financing Receivable, Recorded Investment [Line Items]
Loans	8,850	8,893
Commercial Real Estate
Financing Receivable, Recorded Investment [Line Items]
Loans	1,260,639	1,269,533	1,190,052
Commercial Real Estate | Pass (Grades 1-6)
Financing Receivable, Recorded Investment [Line Items]
Loans	1,229,524	1,247,190
Commercial Real Estate | Special Mention (Grade 7)
Financing Receivable, Recorded Investment [Line Items]
Loans	15,072	7,921
Commercial Real Estate | Substandard (Grade 8)
Financing Receivable, Recorded Investment [Line Items]
Loans	16,043	14,422
Commercial
Financing Receivable, Recorded Investment [Line Items]
Loans	428,676	381,780	386,393
Commercial | Pass (Grades 1-6)
Financing Receivable, Recorded Investment [Line Items]
Loans	423,281	374,429
Commercial | Special Mention (Grade 7)
Financing Receivable, Recorded Investment [Line Items]
Loans	2,051	3,688
Commercial | Substandard (Grade 8)
Financing Receivable, Recorded Investment [Line Items]
Loans	3,344	3,663
Home Equity
Financing Receivable, Recorded Investment [Line Items]
Loans	323,536	327,763	323,671
Home Equity | Performing
Financing Receivable, Recorded Investment [Line Items]
Loans	320,866	325,917
Home Equity | Non-performing
Financing Receivable, Recorded Investment [Line Items]
Loans	2,670	1,846
Consumer
Financing Receivable, Recorded Investment [Line Items]
Loans	23,665	20,624	19,506
Consumer | Performing
Financing Receivable, Recorded Investment [Line Items]
Loans	23,284	20,595
Consumer | Non-performing
Financing Receivable, Recorded Investment [Line Items]
Loans	381	29
HPFC Portfolio Segment
Financing Receivable, Recorded Investment [Line Items]
Loans	28,016	33,656	$ 39,997
HPFC Portfolio Segment | Performing
Financing Receivable, Recorded Investment [Line Items]
Loans	26,758	32,261
HPFC Portfolio Segment | Substandard (Grade 8)
Financing Receivable, Recorded Investment [Line Items]
Loans	98	123
HPFC Portfolio Segment | Non-performing
Financing Receivable, Recorded Investment [Line Items]
Loans	$ 1,160	$ 1,272