LOANS AND ALLOWANCE FOR LOAN LOSSES (Credit Risk Exposure Indicators by Portfolio Segment) (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019	Jun. 30, 2019
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	$ 3,326,041	$ 3,095,023	$ 3,100,324
Pass (Grades 1-6)
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	2,948,639	2,696,045
Performing
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	311,365	336,401
Special Mention (Grade 7)
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	17,274	34,859
Substandard (Grade 8)
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	46,394	25,568
Non-performing
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	2,369	2,150
Residential Real Estate
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	1,054,333	1,070,374	1,035,792
Residential Real Estate | Pass (Grades 1-6)
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	1,046,718	1,062,825
Residential Real Estate | Special Mention (Grade 7)
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	409	473
Residential Real Estate | Substandard (Grade 8)
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	7,206	7,076
Commercial Real Estate
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	1,310,985	1,243,397	1,260,639
Commercial Real Estate | Pass (Grades 1-6)
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	1,260,532	1,196,683
Commercial Real Estate | Special Mention (Grade 7)
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	15,711	31,753
Commercial Real Estate | Substandard (Grade 8)
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	34,742	14,961
Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	411,225	421,108	428,676
Commercial | Pass (Grades 1-6)
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	406,475	415,870
Commercial | Special Mention (Grade 7)
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	1,154	2,544
Commercial | Substandard (Grade 8)
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	3,596	2,694
SBA PPP Portfolio Segment
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	218,803	0	0
SBA PPP Portfolio Segment | Pass (Grades 1-6)
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	218,803
Home Equity
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	290,815	312,779	323,536
Home Equity | Performing
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	288,451	310,653
Home Equity | Non-performing
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	2,364	2,126
Consumer
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	22,919	25,772	23,665
Consumer | Performing
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	22,914	25,748
Consumer | Non-performing
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	5	24
HPFC Portfolio Segment
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	16,961	21,593	$ 28,016
HPFC Portfolio Segment | Pass (Grades 1-6)
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	16,111	20,667
HPFC Portfolio Segment | Special Mention (Grade 7)
Financing Receivable, Credit Quality Indicator [Line Items]
Loans		89
HPFC Portfolio Segment | Substandard (Grade 8)
Financing Receivable, Credit Quality Indicator [Line Items]
Loans	$ 850	$ 837