Commitments and Contingencies (Details) $ in Thousands	12 Months Ended
Dec. 31, 2017 USD ($) Commitment	Dec. 31, 2016 USD ($) Commitment
Financial instruments whose contract amount represents credit risk [Abstract]
Repurchases of loans previously sold	$ 469	$ 343
Deposits	602,228	571,946
Loan balances	660,096	601,309
Interest income	24,594	22,189
Non-interest income	5,238	7,071
Cannabis Customers [Member]
Financial instruments whose contract amount represents credit risk [Abstract]
Deposits	19,200
Loan balances	$ 11,900
Percentage of deposits in total deposits	3.20%
Percentage of loans in total loans	1.80%
Interest income	$ 280
Non-interest income	230
Volume of deposits accepted	45,100
Standby Letters of Credit [Member]
Financial instruments whose contract amount represents credit risk [Abstract]
Off-balance sheet credit risk	$ 3,480	4,022
Letters of credit expiry period	12 months
Current liability for guarantees	$ 42	94
Home Equity Lines of Credit [Member]
Financial instruments whose contract amount represents credit risk [Abstract]
Off-balance sheet credit risk	$ 13,321	7,736
Loan expiry period	10 years
Unadvanced Construction Commitments [Member]
Financial instruments whose contract amount represents credit risk [Abstract]
Off-balance sheet credit risk	$ 74,720	15,728
Mortgage Loan Commitments [Member]
Financial instruments whose contract amount represents credit risk [Abstract]
Off-balance sheet credit risk	$ 595	$ 574
Number of mortgage loan commitments at fixed interest rate \| Commitment	2	2
Fixed interest rate		4.25%
Fixed rate loan commitments	$ 595	$ 574
Mortgage Loan Commitments [Member] \| Loan 1 [Member]
Financial instruments whose contract amount represents credit risk [Abstract]
Fixed interest rate	5.00%
Mortgage Loan Commitments [Member] \| Loan 2 [Member]
Financial instruments whose contract amount represents credit risk [Abstract]
Fixed interest rate	3.875%
Lines of Credit [Member]
Financial instruments whose contract amount represents credit risk [Abstract]
Off-balance sheet credit risk	$ 16,612	34,125
Loans Sold and Serviced with Limited Repurchase Provisions [Member]
Financial instruments whose contract amount represents credit risk [Abstract]
Off-balance sheet credit risk	21,409	70,773
Mortgage loan, held in reserve	63	48
Repurchases of loans previously sold	$ 469	$ 343
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
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

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

Number of mortgage commitments at fixed 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_NumberOfMortgageCommitmentsAtFixedRateOfInterest
Namespace Prefix:	svbi_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

The cash outflow associated with repurchasing of loans previously sold during the period.

+ References

No definition available.

+ Details

Name:	svbi_PaymentsToRepurchasesOfLoansPreviouslySold
Namespace Prefix:	svbi_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Refers to the percentage of loans in total loans.

+ References

No definition available.

+ Details

Name:	svbi_PercentageOfLoansInTotalLoans
Namespace Prefix:	svbi_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- 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

Volume of deposits accepted in the accounts of medical-use cannabis customers during the year.

+ References

No definition available.

+ Details

Name:	svbi_VolumeOfDepositsAccepted
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 aggregate of all deposit liabilities held by the entity, including foreign and domestic, interest and noninterest bearing; may include demand deposits, saving deposits, Negotiable Order of Withdrawal (NOW) and time deposits among others.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.12)
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

+ Details

Name:	us-gaap_Deposits
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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 net amount of operating interest income (expense).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 225
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04.10)
-URI http://asc.fasb.org/extlink&oid=6879574&loc=d3e536633-122882

+ Details

Name:	us-gaap_InterestIncomeExpenseNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- 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

Amount after allowance and deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Includes loans held for sale. Excludes 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 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.7(a))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

+ Details

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

- Definition

Amount of loan with fixed rate of interest.

+ 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=82891408&loc=d3e4428-111522

+ Details

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

- Definition

The total amount of noninterest income which may be derived from: (1) fees and commissions; (2) premiums earned; (3) insurance policy charges; (4) the sale or disposal of assets; and (5) other sources not otherwise specified.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 225
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04.13)
-URI http://asc.fasb.org/extlink&oid=6879574&loc=d3e536633-122882

+ Details

Name:	us-gaap_NoninterestIncome
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Percentage of interest-bearing domestic deposit liabilities to total deposit liabilities.

+ References

No definition available.

+ Details

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

- Details

Name:	us-gaap_MajorCustomersAxis=svbi_CannabisCustomersMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- 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_ProductOrServiceAxis=svbi_Loan1Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ProductOrServiceAxis=svbi_Loan2Member
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:

- 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: