SECURITIES - Composition of Securities (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Amortized cost (1)
Available-for-sale
Municipal bonds	$ 6,528	$ 15,800
Mortgage-backed securities, U.S. Government agencies and U.S. Government-sponsored enterprises	48,866	53,407
Collateralized mortgage obligations, U.S. Government Agencies	8,694	1,470
Collateralized mortgage obligations, Non-agency	2,733	3,327
SBA bonds	10,488	2,056
CRA mutual funds	842	834
Corporate bonds	2,000	2,000
Preferred stock	7	7
Total securities available-for-sale	80,158	78,901
Non-marketable securities
Federal Home Loan Bank of Boston stock	3,452	3,211
Gross unrealized gains
Available-for-sale
Municipal bonds	71	197
Mortgage-backed securities, U.S. Government agencies and U.S. Government-sponsored enterprises	271	229
Collateralized mortgage obligations, U.S. Government Agencies	66	4
Collateralized mortgage obligations, Non-agency	419	414
SBA bonds	23	9
CRA mutual funds
Corporate bonds	45	16
Preferred stock	159	215
Total securities available-for-sale	1,054	1,084
Non-marketable securities
Federal Home Loan Bank of Boston stock
Gross unrealized losses
Available-for-sale
Municipal bonds		1
Mortgage-backed securities, U.S. Government agencies and U.S. Government-sponsored enterprises	173	335
Collateralized mortgage obligations, U.S. Government Agencies	1
Collateralized mortgage obligations, Non-agency	8	6
SBA bonds	3	1
CRA mutual funds	11	16
Corporate bonds		3
Preferred stock
Total securities available-for-sale	196	362
Non-marketable securities
Federal Home Loan Bank of Boston stock
Fair value
Available-for-sale
Municipal bonds	6,599	15,996
Mortgage-backed securities, U.S. Government agencies and U.S. Government-sponsored enterprises	48,964	53,301
Collateralized mortgage obligations, U.S. Government Agencies	8,759	1,474
Collateralized mortgage obligations, Non-agency	3,144	3,735
SBA bonds	10,508	2,064
CRA mutual funds	831	818
Corporate bonds	2,045	2,013
Preferred stock	166	222
Total securities available-for-sale	81,016	79,623
Non-marketable securities
Federal Home Loan Bank of Boston stock	$ 3,452	$ 3,211

No definition available.

Name:	SAL_CorporateBondsAtCarryingValue
Namespace Prefix:	SAL_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Investments in notes or bonds that are collateralized by a specific group of underlying assets owned by the issuer of the notes or bonds which are short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Generally, only investments with original maturities of three months or less qualify under that definition. Original maturity means original maturity to the entity holding the investment. For example, both a three-month US Treasury bill and a three-year Treasury note purchased three months from maturity qualify as cash equivalents. However, a Treasury note purchased three-years ago does not become a cash equivalent when its remaining maturity is three months.

+ References

No definition available.

+ Details

Name:	us-gaap_AssetBackedSecuritiesAtCarryingValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 25
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=75030427&loc=d3e22054-111558

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 5
-Subparagraph (aa)
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27232-111563

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=82896770&loc=d3e26610-111562

+ Details

Name:	us-gaap_AvailableForSaleSecurities
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- References

No definition available.

+ Details

Name:	us-gaap_AvailableForSaleSecuritiesAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The total of collateralized agreements including securities purchased under agreements to resell (repos), borrowed securities, and secured demand notes.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(m)(2)(i)(A))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 10
-Section 05
-Paragraph 16
-URI http://asc.fasb.org/extlink&oid=64836671&loc=d3e93640-111703

+ Details

Name:	us-gaap_CollateralizedAgreements
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of securities, mortgage loans, or other financial instruments pledged as collateral for deposits.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 405
-Section 50
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=50488274&loc=d3e64164-112818

+ Details

Name:	us-gaap_DepositLiabilitiesCollateralIssuedFinancialInstruments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of Federal Home Loan Bank (FHLB) and Federal Reserve Bank stock.

+ References

No definition available.

+ Details

Name:	us-gaap_FederalHomeLoanBankStockAndFederalReserveBankStock
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- References

No definition available.

+ Details

Name:	us-gaap_HeldToMaturitySecuritiesAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

For an unclassified balance sheet, this item represents investments in common and preferred stocks and other forms of securities that provide ownership interests in a corporation.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.1(b))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

+ Details

Name:	us-gaap_MarketableSecuritiesEquitySecurities
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Investment in short-term money-market instruments (such as commercial paper, banker's acceptances, repurchase agreements, government securities, certificates of deposit, and so forth) which are highly liquid (that is, readily convertible to known amounts of cash) and so near their maturity that they present an insignificant risk of changes in value because of changes in interest rates. Generally, only investments with original maturities of three months or less qualify as cash equivalents by definition. Original maturity means an original maturity to the entity holding the investment. For example, both a three-month US Treasury bill and a three-year Treasury note purchased three months from maturity qualify as cash equivalents. However, a Treasury note purchased three-years ago does not become a cash equivalent when its remaining maturity is three months.

+ References

No definition available.

+ Details

Name:	us-gaap_MoneyMarketFundsAtCarryingValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Fair value of securitized, pay-through debt securities collateralized by real estate mortgage loans classified as available-for-sale.

+ References

No definition available.

+ Details

Name:	us-gaap_MortgageBackedSecuritiesAvailableForSaleFairValueDisclosure
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Bonds or similar securities issued by state, city, or local governments or the agencies operated by state, city, or local governments which are short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Generally, only investments with original maturities of three months or less qualify under that definition. Original maturity means original maturity to the entity holding the investment. For example, both a three-month US Treasury bill and a three-year Treasury note purchased three months from maturity qualify as cash equivalents. However, a Treasury note purchased three-years ago does not become a cash equivalent when its remaining maturity is three months.

+ References

No definition available.

+ Details

Name:	us-gaap_MunicipalDebtSecuritiesAtCarryingValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

Name:	us-gaap_GainLossOnInvestmentsByCategoryAxis=us-gaap_CostmethodInvestmentsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_GainLossOnInvestmentsByCategoryAxis=SAL_AccumulatedOtherComprehensiveIncomeGainMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_GainLossOnInvestmentsByCategoryAxis=SAL_AccumulatedOtherComprehensiveIncomeLossMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_GainLossOnInvestmentsByCategoryAxis=us-gaap_AvailableforsaleSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: