LOANS AND ALLOWANCE FOR LOAN LOSSES (Narrative) (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2018 USD ($) loan	Sep. 30, 2017 USD ($) loan	Sep. 30, 2018 USD ($) loan	Sep. 30, 2017 USD ($) loan	Jun. 30, 2018 USD ($)	Dec. 31, 2017 USD ($)	Jun. 30, 2017 USD ($)	Dec. 31, 2016 USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-Accrual Loans	$ 14,877,000		$ 14,877,000			$ 15,314,000
Other industry exposures			0
Interest lost on nonaccrual loans	$ 171,000	$ 187,000	$ 507,000	$ 673,000
Number of TDRs | loan	2	3	3	5
Loans modified | loan	0	0	1	0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 0	$ 0	$ 299,000	$ 0
Financing Receivable, Individually Evaluated for Impairment	12,112,000	13,430,000	12,112,000	13,430,000		13,590,000
Proceeds from the sale of mortgage loans			159,740,000	155,086,000
Gain on sale of mortgage loans			4,126,000	4,323,000
Loans held for sale, at fair value	10,158,000		10,158,000			8,103,000
Financing Receivable, Allowance for Credit Losses	23,526,000	24,413,000	23,526,000	24,413,000	$ 23,668,000	24,171,000	$ 24,394,000	$ 23,116,000
FHLB advances, general debt obligations, pledged collateral	1,200,000,000		1,200,000,000			1,100,000,000
Derivative, Fair Value, Net	241,000		241,000			142,000
Unrealized Gain (Loss) on Derivatives	(46,000)	(60,000)	(38,000)	(283,000)
Allowance Related to Troubled Debt Restructurings assigned during period	57,000	29,000	96,000	44,000
Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans restructured due to credit difficulties that are now performing	4,000,000		4,000,000			5,000,000
Financing receivables impaired TDR non-performing	1,600,000		1,600,000			1,200,000
Residential Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-Accrual Loans	4,720,000		4,720,000			4,979,000
Financing Receivable, Individually Evaluated for Impairment	5,184,000	4,792,000	5,184,000	4,792,000		5,171,000
Mortgage Loans in Process of Foreclosure, Amount	1,300,000		1,300,000			1,900,000
Financing Receivable, Allowance for Credit Losses	5,760,000	4,542,000	5,760,000	4,542,000	5,779,000	5,086,000	4,481,000	4,160,000
Commercial Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-Accrual Loans	5,517,000		5,517,000			5,642,000
Financing Receivable, Individually Evaluated for Impairment	5,007,000	6,373,000	5,007,000	6,373,000		6,199,000
Financing Receivable, Allowance for Credit Losses	10,582,000	12,796,000	10,582,000	12,796,000	10,310,000	11,863,000	12,848,000	12,154,000
Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-Accrual Loans	2,402,000		2,402,000			2,000,000
Financing Receivable, Individually Evaluated for Impairment	1,548,000	1,842,000	1,548,000	1,842,000		1,791,000
Financing Receivable, Allowance for Credit Losses	3,968,000	4,221,000	3,968,000	4,221,000	4,303,000	4,171,000	4,275,000	3,755,000
Home Equity
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-Accrual Loans	1,614,000		1,614,000			1,650,000
Financing Receivable, Individually Evaluated for Impairment	373,000	423,000	373,000	423,000		429,000
Financing Receivable, Allowance for Credit Losses	2,575,000	2,177,000	2,575,000	2,177,000	2,616,000	2,367,000	2,094,000	2,194,000
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-Accrual Loans	33,000		33,000			0
Financing Receivable, Individually Evaluated for Impairment	0	0	0	0
Financing Receivable, Allowance for Credit Losses	273,000	195,000	273,000	195,000	260,000	233,000	182,000	181,000
HPFC Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-Accrual Loans	591,000		591,000			1,043,000
Financing Receivable, Individually Evaluated for Impairment	0	0	0	0
Financing Receivable, Allowance for Credit Losses	368,000	482,000	368,000	482,000	$ 400,000	451,000	$ 514,000	$ 672,000
Fixed Rate Residential Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Proceeds from the sale of mortgage loans	58,400,000	59,900,000	155,600,000	150,800,000
Gain on sale of mortgage loans	1,500,000	1,600,000	4,100,000	$ 4,300,000
Loans held for sale, at fair value	10,200,000		10,200,000			8,100,000
Home Equity Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of TDRs | loan				1
Allowance Related to Troubled Debt Restructurings assigned during period			114,000
Nonoperating Income (Expense) | Fixed Rate Residential Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gain on sale of mortgage loans	$ (99,000)	72,000	(67,000)	$ 263,000
Unrealized gain (loss) on loans held for sale			$ (30,000)	37,000
Minimum
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Months	18		18
Minimum | HPFC Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Term to maturity	7 years
Maximum
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Months	24		24
Maximum | HPFC Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Term to maturity	10 years
Non-Residential Building Operators Industry Sector | Loan Concentration Risk | Total Loan Portfolio
Accounts, Notes, Loans and Financing Receivable [Line Items]
Concentration risk (percentage)			11.00%
Non-Residential Building Operators Industry Sector | Loan Concentration Risk | Commercial Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Concentration risk (percentage)			25.00%
Substandard (Grade 8) | Minimum
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Individually Evaluated for Impairment	$ 500,000		$ 500,000
Forward Contracts [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Derivative, Fair Value, Net	241,000		241,000			$ 142,000
Unrealized Gain (Loss) on Derivatives	$ 49,000	$ 16,000	$ 99,000	$ 35,000