LOANS AND ALLOWANCE FOR LOAN LOSSES (Narrative) (Details)	3 Months Ended		12 Months Ended
	Mar. 31, 2019 USD ($) loan	Mar. 31, 2018 USD ($) loan	Dec. 31, 2018 USD ($)	Jun. 30, 2018 USD ($)	Dec. 31, 2017 USD ($)	Jun. 30, 2017 USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Related Parties, Description	At March 31, 2019 and 2018, outstanding loans to certain officers, directors and their associated companies was less than 5% of the Company's shareholders' equity.	At March 31, 2019 and 2018, outstanding loans to certain officers, directors and their associated companies was less than 5% of the Company's shareholders' equity.
Non-Accrual Loans	$ 10,153,000		$ 10,530,000
Other industry exposures	0
Interest lost on nonaccrual loans	$ 109,000	$ 162,000
Number of TDRs | loan	0	0
Loans modified | loan	0	0
Financing Receivable, Individually Evaluated for Impairment	$ 6,264,000	$ 11,225,000	6,926,000
Proceeds from the sale of mortgage loans	28,834,000	46,426,000
Gain on sale of mortgage loans	826,000	1,220,000
Loans held for sale, at fair value (book value of $8,711 and $4,314, respectively)	8,795,000		4,403,000
Financing Receivable, Allowance for Credit Losses	25,201,000	22,990,000	24,712,000	$ 24,712,000	$ 24,171,000	$ 24,171,000
FHLB advances, general debt obligations, pledged collateral	1,300,000,000		1,100,000,000
Derivative, Fair Value, Net	98,000		15,000
Unrealized Gain (Loss) on Derivatives	(181,000)	(12,000)
Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans restructured due to credit difficulties that are now performing	3,800,000		3,900,000
Financing receivables impaired TDR non-performing	600,000		500,000
Residential Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-Accrual Loans	5,415,000		5,492,000
Financing Receivable, Individually Evaluated for Impairment	4,736,000	5,059,000	4,762,000
Mortgage Loans in Process of Foreclosure, Amount	2,700,000		2,300,000
Financing Receivable, Allowance for Credit Losses	6,153,000	5,497,000	6,071,000	6,071,000	5,086,000	5,086,000
Commercial Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-Accrual Loans	975,000		1,380,000
Financing Receivable, Individually Evaluated for Impairment	410,000	3,961,000	930,000
Financing Receivable, Allowance for Credit Losses	11,838,000	10,286,000	11,654,000	11,654,000	11,863,000	11,863,000
Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-Accrual Loans	802,000		1,279,000
Financing Receivable, Individually Evaluated for Impairment	223,000	1,714,000	786,000
Financing Receivable, Allowance for Credit Losses	3,616,000	4,126,000	3,620,000	3,620,000	4,171,000	4,171,000
Home Equity
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-Accrual Loans	2,467,000		1,846,000
Financing Receivable, Individually Evaluated for Impairment	895,000	491,000	442,000
Financing Receivable, Allowance for Credit Losses	3,027,000	2,427,000	2,796,000	2,796,000	2,367,000	2,367,000
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-Accrual Loans	9,000		15,000
Financing Receivable, Individually Evaluated for Impairment	0	0	6,000
Financing Receivable, Allowance for Credit Losses	259,000	230,000	234,000	234,000	233,000	233,000
HPFC Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-Accrual Loans	485,000		518,000
Financing Receivable, Individually Evaluated for Impairment	0	0
Financing Receivable, Allowance for Credit Losses	308,000	424,000	337,000	$ 337,000	$ 451,000	$ 451,000
Fixed Rate Residential Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Proceeds from the sale of mortgage loans	28,000,000	45,200,000
Gain on sale of mortgage loans	800,000	1,200,000
Loans held for sale, at fair value (book value of $8,711 and $4,314, respectively)	8,700,000		4,300,000
Nonoperating Income (Expense) | Fixed Rate Residential Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gain on sale of mortgage loans	(4,000)	9,000
Unrealized gain (loss) on loans held for sale	$ 84,000		89,000
Minimum
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Months	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
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)	12.00%
Non-Residential Building Operators Industry Sector | Loan Concentration Risk | Commercial Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Concentration risk (percentage)	28.00%
Substandard (Grade 8) | Minimum
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Individually Evaluated for Impairment	$ 500,000
Forward Contracts [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Derivative, Fair Value, Net	98,000		$ 15,000
Unrealized Gain (Loss) on Derivatives	$ 83,000	$ 19,000