FAIR VALUE OF ASSETS AND LIABILITIES - Carrying value and estimated fair values of financial instruments (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Carrying value
Financial Assets
Cash and cash equivalents	$ 61,392	$ 35,485
Securities available-for-sale	81,016	79,623
Federal Home Loan Bank stock	3,452	3,211
Loans held-for-sale	594
Loans receivable, net	771,850	763,184
Accrued interest receivable	2,303	2,424
Cash surrender value of life insurance	14,211	14,038
Financial Liabilities
Demand (non-interest-bearing)	219,660	218,420
Demand (interest-bearing)	132,899	127,854
Money market	194,704	182,476
Savings and other	145,937	135,435
Certificates of deposit	118,141	117,585
Deposits	811,341	781,770
Repurchase agreements	2,126	5,535
FHLBB advances	47,302	37,188
Subordinated debt	9,799	9,788
Note payable	327	344
Capital lease liability	1,987	418
Accrued interest payable	88	89
Estimated fair value
Financial Assets
Cash and cash equivalents	61,392	35,485
Securities available-for-sale	81,016	79,623
Federal Home Loan Bank stock	3,452	3,211
Loans held-for-sale	594
Loans receivable, net	787,484	774,442
Accrued interest receivable	2,303	2,424
Cash surrender value of life insurance	14,211	14,038
Financial Liabilities
Demand (non-interest-bearing)	219,660	218,420
Demand (interest-bearing)	132,899	127,854
Money market	194,704	182,476
Savings and other	145,937	135,435
Certificates of deposit	119,107	118,610
Deposits	812,307	782,795
Repurchase agreements	2,126	5,535
FHLBB advances	48,286	38,440
Subordinated debt	10,433	10,378
Note payable	360	377
Capital lease liability	2,285	841
Accrued interest payable	88	89
Fair Value Measurements Using - Level 1
Financial Assets
Cash and cash equivalents	61,392	35,485
Securities available-for-sale	997	1,040
Federal Home Loan Bank stock
Loans held-for-sale
Loans receivable, net
Accrued interest receivable
Cash surrender value of life insurance	14,211	14,038
Financial Liabilities
Demand (non-interest-bearing)
Demand (interest-bearing)
Money market
Savings and other
Certificates of deposit
Deposits
Repurchase agreements
FHLBB advances
Subordinated debt
Note payable
Capital lease liability
Accrued interest payable
Fair Value Measurements Using - Level 2
Financial Assets
Cash and cash equivalents
Securities available-for-sale	80,019	78,583
Federal Home Loan Bank stock	3,452	3,211
Loans held-for-sale
Loans receivable, net
Accrued interest receivable
Cash surrender value of life insurance
Financial Liabilities
Demand (non-interest-bearing)
Demand (interest-bearing)
Money market
Savings and other
Certificates of deposit
Deposits
Repurchase agreements
FHLBB advances
Subordinated debt
Note payable
Capital lease liability
Accrued interest payable
Fair Value Measurements Using - Level 3
Financial Assets
Cash and cash equivalents
Securities available-for-sale
Federal Home Loan Bank stock
Loans held-for-sale	594
Loans receivable, net	787,484	774,442
Accrued interest receivable	2,303	2,424
Cash surrender value of life insurance
Financial Liabilities
Demand (non-interest-bearing)	219,660	218,420
Demand (interest-bearing)	132,899	127,854
Money market	194,704	182,476
Savings and other	145,937	135,435
Certificates of deposit	119,107	118,610
Deposits	812,307	782,795
Repurchase agreements	2,126	5,535
FHLBB advances	48,286	38,440
Subordinated debt	10,433	10,378
Note payable	360	377
Capital lease liability	2,285	841
Accrued interest payable	$ 88	$ 89