FINANCIAL INSTRUMENTS - Financial instrument liabilities with off-balance sheet credit risk (Details) (Financial instrument liabilities with off-balance sheet credit risk, USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Financial instrument liabilities with off-balance sheet credit risk
Residential	$ 3,030	$ 314
Home equity credit	25,882	28,377
Commercial	16,751	9,900
Land	5	10
Real estate secured	45,668	38,601
Commercial and industrial	57,905	17,563
Consumer	1,537	1,321
Unadvanced portions of loans	105,110	57,485
Commitments to originate loans	20,953	9,730
Standby letters of credit	3,422	3,422
Total	$ 129,485	$ 67,268

FINANCIAL INSTRUMENTS - Financial instrument liabilities with off-balance sheet credit risk (Details) (Financial instrument liabilities with off-balance sheet credit risk, USD $)
In Thousands, unless otherwise specified

Dec. 31, 2014

Dec. 31, 2013

Financial instrument liabilities with off-balance sheet credit risk

Residential

$ 3,030us-gaap_LoansAndLeasesReceivableConsumerLoansInProcess
/ us-gaap_FairValueEstimateNotPracticableDisclosureItemsAxis
= us-gaap_FairValueEstimateNotPracticableCarryingReportedAmountMember

$ 314us-gaap_LoansAndLeasesReceivableConsumerLoansInProcess
/ us-gaap_FairValueEstimateNotPracticableDisclosureItemsAxis
= us-gaap_FairValueEstimateNotPracticableCarryingReportedAmountMember

Home equity credit

25,882us-gaap_LoansAndLeasesReceivableOtherLoansInProcess
/ us-gaap_FairValueEstimateNotPracticableDisclosureItemsAxis
= us-gaap_FairValueEstimateNotPracticableCarryingReportedAmountMember

28,377us-gaap_LoansAndLeasesReceivableOtherLoansInProcess
/ us-gaap_FairValueEstimateNotPracticableDisclosureItemsAxis
= us-gaap_FairValueEstimateNotPracticableCarryingReportedAmountMember

Commercial

16,751us-gaap_LoansAndLeasesReceivableCommercialLoansInProcess
/ us-gaap_FairValueEstimateNotPracticableDisclosureItemsAxis
= us-gaap_FairValueEstimateNotPracticableCarryingReportedAmountMember

9,900us-gaap_LoansAndLeasesReceivableCommercialLoansInProcess
/ us-gaap_FairValueEstimateNotPracticableDisclosureItemsAxis
= us-gaap_FairValueEstimateNotPracticableCarryingReportedAmountMember

Land

5us-gaap_GroundLeasesAccumulatedAmortization
/ us-gaap_FairValueEstimateNotPracticableDisclosureItemsAxis
= us-gaap_FairValueEstimateNotPracticableCarryingReportedAmountMember

10us-gaap_GroundLeasesAccumulatedAmortization
/ us-gaap_FairValueEstimateNotPracticableDisclosureItemsAxis
= us-gaap_FairValueEstimateNotPracticableCarryingReportedAmountMember

Real estate secured

45,668us-gaap_RealEstateLiabilitiesAssociatedWithAssetsHeldForDevelopmentAndSale
/ us-gaap_FairValueEstimateNotPracticableDisclosureItemsAxis
= us-gaap_FairValueEstimateNotPracticableCarryingReportedAmountMember

38,601us-gaap_RealEstateLiabilitiesAssociatedWithAssetsHeldForDevelopmentAndSale
/ us-gaap_FairValueEstimateNotPracticableDisclosureItemsAxis
= us-gaap_FairValueEstimateNotPracticableCarryingReportedAmountMember

Commercial and industrial

57,905us-gaap_LoansAndLeasesReceivableDeferredIncomeCommercial
/ us-gaap_FairValueEstimateNotPracticableDisclosureItemsAxis
= us-gaap_FairValueEstimateNotPracticableCarryingReportedAmountMember

17,563us-gaap_LoansAndLeasesReceivableDeferredIncomeCommercial
/ us-gaap_FairValueEstimateNotPracticableDisclosureItemsAxis
= us-gaap_FairValueEstimateNotPracticableCarryingReportedAmountMember

Consumer

1,537us-gaap_LoansAndLeasesReceivableDeferredIncomeConsumer
/ us-gaap_FairValueEstimateNotPracticableDisclosureItemsAxis
= us-gaap_FairValueEstimateNotPracticableCarryingReportedAmountMember

1,321us-gaap_LoansAndLeasesReceivableDeferredIncomeConsumer
/ us-gaap_FairValueEstimateNotPracticableDisclosureItemsAxis
= us-gaap_FairValueEstimateNotPracticableCarryingReportedAmountMember

Unadvanced portions of loans

105,110us-gaap_LoansAndLeasesReceivableDeferredIncomeOther
/ us-gaap_FairValueEstimateNotPracticableDisclosureItemsAxis
= us-gaap_FairValueEstimateNotPracticableCarryingReportedAmountMember

57,485us-gaap_LoansAndLeasesReceivableDeferredIncomeOther
/ us-gaap_FairValueEstimateNotPracticableDisclosureItemsAxis
= us-gaap_FairValueEstimateNotPracticableCarryingReportedAmountMember

Commitments to originate loans

20,953us-gaap_LoansAndLeasesReceivableDeferredIncome
/ us-gaap_FairValueEstimateNotPracticableDisclosureItemsAxis
= us-gaap_FairValueEstimateNotPracticableCarryingReportedAmountMember

9,730us-gaap_LoansAndLeasesReceivableDeferredIncome
/ us-gaap_FairValueEstimateNotPracticableDisclosureItemsAxis
= us-gaap_FairValueEstimateNotPracticableCarryingReportedAmountMember

Standby letters of credit

3,422us-gaap_GuaranteesFairValueDisclosure
/ us-gaap_FairValueEstimateNotPracticableDisclosureItemsAxis
= us-gaap_FairValueEstimateNotPracticableCarryingReportedAmountMember

Total

$ 129,485us-gaap_LoansAndLeasesReceivableLoansInProcess
/ us-gaap_FairValueEstimateNotPracticableDisclosureItemsAxis
= us-gaap_FairValueEstimateNotPracticableCarryingReportedAmountMember

$ 67,268us-gaap_LoansAndLeasesReceivableLoansInProcess
/ us-gaap_FairValueEstimateNotPracticableDisclosureItemsAxis
= us-gaap_FairValueEstimateNotPracticableCarryingReportedAmountMember

- Definition

Accumulated amortization on long-term land leases capitalized as part of real property.

+ References

No definition available.

+ Details

Name:	us-gaap_GroundLeasesAccumulatedAmortization
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Fair value portion of guarantee, including, but not limited to, financial standby letter of credit, fair value guarantee, guarantee of collection of scheduled contractual cash flows from financial assets, and contracts that contingently require the guarantor to make payments or perform services.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 460

-SubTopic 10

-Section 50

-Paragraph 5

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=6851643&loc=d3e12201-110248

+ Details

Name:	us-gaap_GuaranteesFairValueDisclosure
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The undisbursed portion of the commercial loan receivable balance (loans in process) which is deducted separately from total loans.

+ References

No definition available.

+ Details

Name:	us-gaap_LoansAndLeasesReceivableCommercialLoansInProcess
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The undisbursed portion of the consumer loan receivable balance (loans in process) which is deducted separately from total loans.

+ References

No definition available.

+ Details

Name:	us-gaap_LoansAndLeasesReceivableConsumerLoansInProcess
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of deferred interest and fee income, unamortized costs incurred to originate loans and leases, unamortized loan commitments and loan syndication fees, and premiums over or discounts from face amounts of acquired loans. Excludes amounts for loans and leases covered under loss sharing agreements.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 4

-URI http://asc.fasb.org/extlink&oid=49124121&loc=d3e5074-111524

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 20

-Section 50

-Paragraph 3

-URI http://asc.fasb.org/extlink&oid=6378556&loc=d3e10152-111534

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 840

-SubTopic 30

-Section 50

-Paragraph 4

-Subparagraph (a)(4)

-URI http://asc.fasb.org/extlink&oid=25496975&loc=d3e45377-112738

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-03.7)

-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

+ Details

Name:	us-gaap_LoansAndLeasesReceivableDeferredIncome
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Reflects the cumulative amount of interest and fees paid by commercial loan borrowers which have not yet been taken into income in conformity with GAAP. Also reflects the amount of unamortized costs incurred to originate loans and leases, unamortized loan commitments and loan syndication fees, and premiums over or discounts from face amounts of acquired loans which have been classified as commercial loans by the entity and that are being amortized into income as an adjustment to yield.

+ References

+ Details

Name:	us-gaap_LoansAndLeasesReceivableDeferredIncomeCommercial
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Reflects the cumulative amount of interest and fees paid by consumer loan borrowers which have not yet been taken into income in conformity with GAAP. Also reflects the amount of unamortized costs incurred to originate loans and leases, unamortized loan commitments and loan syndication fees, and premiums over or discounts from face amounts of acquired loans which have been classified as consumer loans by the entity and that are being amortized into income as an adjustment to yield.

+ References

+ Details

Name:	us-gaap_LoansAndLeasesReceivableDeferredIncomeConsumer
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Reflects the cumulative amount of interest and fees paid by borrowers, for loans not otherwise defined in the taxonomy, which have not yet been taken into income in conformity with GAAP. Also reflects the amount of unamortized costs incurred to originate loans and leases, unamortized loan commitments and loan syndication fees, and premiums over or discounts from face amounts of acquired loans which are not otherwise defined in the taxonomy and which are being amortized into income as an adjustment to yield.

+ References

+ Details

Name:	us-gaap_LoansAndLeasesReceivableDeferredIncomeOther
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of undisbursed portion of the loan receivable balance (loans in process). Excludes loans and leases covered under loss sharing agreements.

+ References

No definition available.

+ Details

Name:	us-gaap_LoansAndLeasesReceivableLoansInProcess
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The undisbursed portion of the other loan receivable balance (loans in process) which is deducted separately from total loans.

+ References

No definition available.

+ Details

Name:	us-gaap_LoansAndLeasesReceivableOtherLoansInProcess
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

For banks, amount of all liabilities for which a financial institution is required to include in its calculation of net investment in real estate assets held for development or sale.

+ References

No definition available.

+ Details

Name:	us-gaap_RealEstateLiabilitiesAssociatedWithAssetsHeldForDevelopmentAndSale
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant