Loans Receivable, Financial Instruments Whose Contract Amounts Represent Credit Risk (Details) $ in Thousands	12 Months Ended
Dec. 31, 2016 USD ($) Commitment Loan	Dec. 31, 2015 USD ($) Commitment Loan
Standby Letters of Credit [Member]
Financial instruments whose contract amount represents credit risk [Abstract]
Off-balance sheet credit risk	$ 4,022	$ 5,937
Current liability for guarantees	$ 94	115
Letters of credit expiry period	12 months
Home Equity Lines of Credit [Member]
Financial instruments whose contract amount represents credit risk [Abstract]
Off-balance sheet credit risk	$ 7,736	7,467
Loan expiry period	10 years
Unadvanced Construction Commitments [Member]
Financial instruments whose contract amount represents credit risk [Abstract]
Off-balance sheet credit risk	$ 15,728	21,101
Mortgage Loan Commitments [Member]
Financial instruments whose contract amount represents credit risk [Abstract]
Off-balance sheet credit risk	574	3,233
Fixed rate loan commitments	$ 574	$ 3,233
Fixed interest rate	4.25%
Number of mortgage loan commitments at floating rate of interest \| Commitment	2	7
Mortgage Loan Commitments [Member] \| Minimum [Member]
Financial instruments whose contract amount represents credit risk [Abstract]
Fixed interest rate		3.75%
Mortgage Loan Commitments [Member] \| Maximum [Member]
Financial instruments whose contract amount represents credit risk [Abstract]
Fixed interest rate		8.00%
Lines of Credit [Member]
Financial instruments whose contract amount represents credit risk [Abstract]
Off-balance sheet credit risk	$ 34,125	$ 27,189
Loans Sold and Serviced with Limited Repurchase Provisions [Member]
Financial instruments whose contract amount represents credit risk [Abstract]
Off-balance sheet credit risk	70,773	65,107
Loans receivable held-for-sale, amount	149,990	157,420
Mortgage loan, held in reserve	48	$ 0
Repurchase of loan	$ 343
Number of repurchased loans \| Loan	0	0
Loans Sold and Serviced with Limited Repurchase Provisions [Member] \| Minimum [Member]
Financial instruments whose contract amount represents credit risk [Abstract]
Period of delinquency under repurchase agreement	120 days	120 days
Loans Sold and Serviced with Limited Repurchase Provisions [Member] \| Maximum [Member]
Financial instruments whose contract amount represents credit risk [Abstract]
Period of delinquency under repurchase agreement	180 days	180 days

No definition available.

Name:	svbi_FinancialInstrumentsWhoseContractAmountRepresentsCreditRiskAbstract
Namespace Prefix:	svbi_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Expiry period of majority of standby letters of credit, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

Name:	svbi_LettersOfCreditExpiryPeriod
Namespace Prefix:	svbi_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Term of home equity line of credit, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

Name:	svbi_LoanExpiryPeriod
Namespace Prefix:	svbi_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of reserve for write-down of a mortgage loan.

+ References

No definition available.

+ Details

Name:	svbi_MortgageLoanHeldInReserve
Namespace Prefix:	svbi_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Refers to number of loans repurchased during the period.

+ References

No definition available.

+ Details

Name:	svbi_NumberOfRepurchasedLoans
Namespace Prefix:	svbi_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of total mortgage commitments at floating rate of interest of loan to purchase or refinance residential real estate such as a home, in which the real estate itself serves as collateral for the loan and in which the interest rate and the amount of each payment remain constant throughout the life of the loan.

+ References

No definition available.

+ Details

Name:	svbi_NumberOfTotalMortgageCommitmentsAtFloatingRateOfInterest
Namespace Prefix:	svbi_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the period of delinquency under repurchase agreement during which the Bank is required to repurchase the loan, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

Name:	svbi_PeriodOfDelinquencyUnderRepurchaseAgreement
Namespace Prefix:	svbi_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Element represents to repurchase of its loan.

+ References

No definition available.

+ Details

Name:	svbi_RepurchaseOfLoan
Namespace Prefix:	svbi_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The face amount of financial liabilities, which are not recognized in the financial statements (off-balance sheet) because they fail to meet some other criterion for recognition.

+ References

No definition available.

+ Details

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

- Definition

The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

+ References

No definition available.

+ Details

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

- Definition

The face amount of loans that will be sold to other entities.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=65884687&loc=d3e4428-111522

+ Details

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

- Definition

Amount of loan with fixed rate of interest.

+ References

+ Details

Name:	us-gaap_LoansReceivableWithFixedRatesOfInterest1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

Name:	us-gaap_LossContingenciesByNatureOfContingencyAxis=us-gaap_StandbyLettersOfCreditMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LossContingenciesByNatureOfContingencyAxis=us-gaap_HomeEquityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LossContingenciesByNatureOfContingencyAxis=svbi_UnadvancedConstructionCommitmentsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LossContingenciesByNatureOfContingencyAxis=svbi_MortgageLoanCommitmentsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=us-gaap_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LossContingenciesByNatureOfContingencyAxis=us-gaap_DomesticLineOfCreditMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LossContingenciesByNatureOfContingencyAxis=us-gaap_ObligationToRepurchaseReceivablesSoldMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: