LOANS AND ALLOWANCE FOR LOAN LOSSES (Credit Risk Exposure Indicators by Portfolio Segment) (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016	Mar. 31, 2016
Financing Receivable, Recorded Investment [Line Items]
Loans	$ 2,645,139	$ 2,594,564	$ 2,492,634
Pass (Grades 1-6)
Financing Receivable, Recorded Investment [Line Items]
Loans	2,221,507	2,173,031
Performing
Financing Receivable, Recorded Investment [Line Items]
Loans	337,943	345,615
Special Mention (Grade 7)
Financing Receivable, Recorded Investment [Line Items]
Loans	22,302	13,966
Substandard (Grade 8)
Financing Receivable, Recorded Investment [Line Items]
Loans	60,398	58,872
Doubtful [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	1,437	1,456
Non-performing
Financing Receivable, Recorded Investment [Line Items]
Loans	1,552	1,624
Residential Real Estate
Financing Receivable, Recorded Investment [Line Items]
Loans	819,639	802,494	811,974
Residential Real Estate | Pass (Grades 1-6)
Financing Receivable, Recorded Investment [Line Items]
Loans	808,075	789,554
Residential Real Estate | Special Mention (Grade 7)
Financing Receivable, Recorded Investment [Line Items]
Loans	952	2,387
Residential Real Estate | Substandard (Grade 8)
Financing Receivable, Recorded Investment [Line Items]
Loans	10,612	10,553
Commercial Real Estate
Financing Receivable, Recorded Investment [Line Items]
Loans	1,096,475	1,050,780	952,481
Commercial Real Estate | Pass (Grades 1-6)
Financing Receivable, Recorded Investment [Line Items]
Loans	1,038,096	1,003,386
Commercial Real Estate | Special Mention (Grade 7)
Financing Receivable, Recorded Investment [Line Items]
Loans	15,625	5,724
Commercial Real Estate | Substandard (Grade 8)
Financing Receivable, Recorded Investment [Line Items]
Loans	42,754	41,670
Commercial
Financing Receivable, Recorded Investment [Line Items]
Loans	333,607	333,639	292,064
Commercial | Pass (Grades 1-6)
Financing Receivable, Recorded Investment [Line Items]
Loans	321,667	321,148
Commercial | Special Mention (Grade 7)
Financing Receivable, Recorded Investment [Line Items]
Loans	5,486	5,598
Commercial | Substandard (Grade 8)
Financing Receivable, Recorded Investment [Line Items]
Loans	5,017	5,437
Commercial | Doubtful [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	1,437	1,456
Home Equity
Financing Receivable, Recorded Investment [Line Items]
Loans	322,826	329,907	344,497
Home Equity | Performing
Financing Receivable, Recorded Investment [Line Items]
Loans	321,278	328,287
Home Equity | Non-performing
Financing Receivable, Recorded Investment [Line Items]
Loans	1,548	1,620
Consumer
Financing Receivable, Recorded Investment [Line Items]
Loans	16,669	17,332	17,189
Consumer | Performing
Financing Receivable, Recorded Investment [Line Items]
Loans	16,665	17,328
Consumer | Non-performing
Financing Receivable, Recorded Investment [Line Items]
Loans	4	4
HPFC Portfolio Segment
Financing Receivable, Recorded Investment [Line Items]
Loans	55,923	60,412	$ 74,429
HPFC Portfolio Segment | Performing
Financing Receivable, Recorded Investment [Line Items]
Loans	53,669	58,943
HPFC Portfolio Segment | Substandard (Grade 8)
Financing Receivable, Recorded Investment [Line Items]
Loans	239	257
HPFC Portfolio Segment | Non-performing
Financing Receivable, Recorded Investment [Line Items]
Loans	$ 2,015	$ 1,212