FAIR VALUE OF ASSETS AND LIABILITIES - Carrying value and estimated fair values of financial instruments (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Carrying value
Financial Assets
Cash and cash equivalents	$ 31,498	$ 62,118
Securities available-for-sale	80,438	76,694
Federal Home Loan Bank stock	3,436	3,176
Loans receivable, net	749,523	699,018
Accrued interest receivable	2,217	2,307
Cash surrender value of life insurance	13,862	13,685
Mortgage servicing rights	391	597
Financial Liabilities
Demand (non-interest-bearing)	189,182	201,340
Demand (interest-bearing)	120,142	125,465
Money market	197,869	183,783
Savings and other	124,019	119,651
Certificates of deposit	123,259	124,294
Deposits	754,471	754,533
Repurchase agreements	3,355	3,914
FHLBB advances	47,083	26,979
Subordinated debt	9,776	9,764
Note payable	358	376
Capital lease liability	420	422
Accrued interest payable	118	150
Estimated fair value
Financial Assets
Cash and cash equivalents	31,498	62,118
Securities available-for-sale	80,438	76,694
Federal Home Loan Bank stock	3,436	3,176
Loans receivable, net	754,270	707,154
Accrued interest receivable	2,217	2,307
Cash surrender value of life insurance	13,862	13,685
Mortgage servicing rights	961	1,383
Financial Liabilities
Demand (non-interest-bearing)	189,182	201,340
Demand (interest-bearing)	120,142	125,465
Money market	197,869	183,783
Savings and other	124,019	119,651
Certificates of deposit	124,556	125,437
Deposits	755,768	755,676
Repurchase agreements	3,355	3,914
FHLBB advances	49,154	28,559
Subordinated debt	10,162	9,764
Note payable	385	405
Capital lease liability	903	870
Accrued interest payable	118	150
Fair Value Measurements Using - Level 1
Financial Assets
Cash and cash equivalents	31,498	62,118
Securities available-for-sale	342	246
Federal Home Loan Bank stock
Loans receivable, net
Accrued interest receivable
Cash surrender value of life insurance	13,862	13,685
Mortgage servicing rights
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	80,096	76,448
Federal Home Loan Bank stock	3,436	3,176
Loans receivable, net
Accrued interest receivable
Cash surrender value of life insurance
Mortgage servicing rights	961	1,383
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 receivable, net	754,270	707,154
Accrued interest receivable	2,217	2,307
Cash surrender value of life insurance
Mortgage servicing rights
Financial Liabilities
Demand (non-interest-bearing)	189,182	201,340
Demand (interest-bearing)	120,142	125,465
Money market	197,869	183,783
Savings and other	124,019	119,651
Certificates of deposit	124,556	125,437
Deposits	755,768	755,676
Repurchase agreements	3,355	3,914
FHLBB advances	49,154	28,559
Subordinated debt	10,162	9,764
Note payable	385	405
Capital lease liability	903	870
Accrued interest payable	$ 118	$ 150