The number of dwelling units commonly found in residential collateralized loans.

No definition available.

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

- Definition

A lending risk assessment ratio that financial institutions and others lenders examine before approving a mortgage.

+ References

No definition available.

+ Details

Name:	svbi_LoanToValueRatio
Namespace Prefix:	svbi_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Loans serviced not included in the accompanying consolidated statements of financial condition, excluding mortgage loans held for sale are sold either with the mortgage servicing rights released or retained by the bank.

+ References

No definition available.

+ Details

Name:	svbi_MortgageLoansServiced
Namespace Prefix:	svbi_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- References

No definition available.

+ Details

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

- Definition

Amount of increase (decrease) of allowance reserve for credit loss.

+ References

+ Details

Name:	us-gaap_AllowanceForLoanAndLeaseLossesPeriodIncreaseDecrease
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	duration

- 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://fasb.org/us-gaap/role/ref/legacyRef
-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

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 30
-Section 50
-Paragraph 4
-Subparagraph (a)(4)
-URI http://asc.fasb.org/extlink&oid=84165051&loc=d3e45377-112738

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5074-111524

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 20
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=84159169&loc=d3e10152-111534

+ Details

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

- Definition

Amount before allowance of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes loans and leases covered under loss sharing agreements.

+ References

+ Details

Name:	us-gaap_LoansAndLeasesReceivableGrossCarryingAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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. Excludes loans and leases covered under loss sharing agreements and loans held for sale.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-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

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-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_LoansAndLeasesReceivableNetReportedAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Carrying amount as of the balance sheet date of loans that have been pledged as collateral for borrowings. If the secured party has the right by contract or custom to sell or re-pledge the collateral, then the debtor reclassifies that asset and report that asset in its statement of financial position separately from other assets not so encumbered.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 30
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=66007379&loc=d3e113888-111728

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5086-111524

+ Details

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

- Details

Name:	us-gaap_InvestmentTypeAxis=us-gaap_FederalNationalMortgageAssociationCertificatesAndObligationsFNMAMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_InvestmentTypeAxis=us-gaap_FederalHomeLoanMortgageCorporationCertificatesAndObligationsFHLMCMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_ResidentialPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ChangeInAccountingEstimateByTypeAxis=us-gaap_ChangeInAccountingMethodAccountedForAsChangeInEstimateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_CommercialPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_CommercialRealEstatePortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_ConstructionLoansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_HomeEquityLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_ConsumerPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Loans Receivable and Allowance for Loan Losses, Summary of Loans Receivable (Details)	3 Months Ended	12 Months Ended
	Mar. 31, 2019 USD ($) item	Dec. 31, 2018 USD ($)	Mar. 31, 2018 USD ($)
Summary of loans receivable [Abstract]
Total loans receivable	$ 677,115,000	$ 685,374,000
Unearned loan fees	(2,895,000)	(3,025,000)
Loans receivable	674,220,000	682,349,000	$ 669,912,000
Loans pledged as collateral	170,400,000
Federal National Mortgage Association [Member]
Summary of loans receivable [Abstract]
Mortgage loans serviced	28,500,000	29,400,000
Federal Home Loan Mortgage Corporation [Member]
Summary of loans receivable [Abstract]
Mortgage loans serviced	14,900,000	15,100,000
Residential Mortgage [Member]
Summary of loans receivable [Abstract]
Total loans receivable	270,979,000	276,389,000
Loans receivable	$ 269,443,000	274,759,000	285,023,000
Loan to value ratio	80.00%
Residential Mortgage [Member] \| Change in Accounting Estimate [Member]
Summary of loans receivable [Abstract]
Allowance allocated increased (decreased)		(600,000)
Residential Mortgage [Member] \| Minimum [Member]
Summary of loans receivable [Abstract]
Number of dwelling units \| item	1
Residential Mortgage [Member] \| Maximum [Member]
Summary of loans receivable [Abstract]
Number of dwelling units \| item	4
Commercial [Member]
Summary of loans receivable [Abstract]
Total loans receivable	$ 44,725,000	35,884,000
Loans receivable	44,725,000	35,884,000	39,015,000
Commercial [Member] \| Change in Accounting Estimate [Member]
Summary of loans receivable [Abstract]
Allowance allocated increased (decreased)		2,200,000
Commercial Real Estate [Member]
Summary of loans receivable [Abstract]
Total loans receivable	238,618,000	244,088,000
Loans receivable	237,259,000	242,693,000	230,336,000
Commercial Real Estate [Member] \| Change in Accounting Estimate [Member]
Summary of loans receivable [Abstract]
Allowance allocated increased (decreased)		(2,700,000)
ADC [Member]
Summary of loans receivable [Abstract]
Total loans receivable	108,933,000	114,540,000
Loans receivable	108,933,000	114,540,000	100,635,000
ADC [Member] \| Change in Accounting Estimate [Member]
Summary of loans receivable [Abstract]
Allowance allocated increased (decreased)		1,100,000
Home Equity/2nds [Member]
Summary of loans receivable [Abstract]
Total loans receivable	12,714,000	13,386,000
Loans receivable	$ 12,714,000	13,386,000	13,853,000
Home Equity/2nds [Member] \| Minimum [Member]
Summary of loans receivable [Abstract]
Number of dwelling units \| item	1
Home Equity/2nds [Member] \| Maximum [Member]
Summary of loans receivable [Abstract]
Number of dwelling units \| item	4
Consumer [Member]
Summary of loans receivable [Abstract]
Total loans receivable	$ 1,146,000	1,087,000
Loans receivable	$ 1,146,000	$ 1,087,000	$ 1,050,000