Value of input used to measure impaired loans.

No definition available.

Name:	svbi_ImpairedLoansMeasurementInput
Namespace Prefix:	svbi_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	instant

- Definition

Value of input used to measure interest-rate lock commitments measured at fair value.

+ References

No definition available.

+ Details

Name:	svbi_InterestRateLockCommitmentsMeasurementInput
Namespace Prefix:	svbi_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	instant

- References

No definition available.

+ Details

Name:	svbi_QuantitativeInformationAboutLevel3FairValueMeasurementsAbstract
Namespace Prefix:	svbi_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of addition (reduction) to the amount at which an asset could be incurred (settled) in a current transaction between willing parties.

+ References

No definition available.

+ Details

Name:	us-gaap_AssetsFairValueAdjustment
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=99377789&loc=d3e19207-110258

+ Details

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

- Definition

Value of input used to measure real estate owned by financial institution by financial institution which is not directly related to its business.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (bbb)(2)
-URI http://asc.fasb.org/extlink&oid=99377789&loc=d3e19207-110258

+ Details

Name:	us-gaap_OtherRealEstateOwnedMeasurementInput
Namespace Prefix:	us-gaap_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	instant

- Definition

Value of input used to measure servicing asset.

+ References

+ Details

Name:	us-gaap_ServicingAssetMeasurementInput
Namespace Prefix:	us-gaap_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	instant

Fair Value of Financial Instruments, Fair Values of Financial Instruments, Assets, Quantitative Information (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2019 USD ($) item	Mar. 31, 2018 USD ($)	Dec. 31, 2018 USD ($) item	Dec. 31, 2017 USD ($)
Nonrecurring [Member] \| Weighted Average [Member] \| Measurement Input, Discount Rate
Quantitative Information about Level 3 Fair Value Measurements [Abstract]
Impaired loan, measurement input \| item			0.067
Nonrecurring [Member] \| Level 3 [Member]
Quantitative Information about Level 3 Fair Value Measurements [Abstract]
Fair value estimate			$ 5,678
Nonrecurring [Member] \| Carrying Value [Member]
Quantitative Information about Level 3 Fair Value Measurements [Abstract]
Fair value estimate			5,678
MSRs [Member]
Quantitative Information about Level 3 Fair Value Measurements [Abstract]
Fair value estimate	$ 400	$ 499	$ 437	$ 477
Valuation adjustment	$ (37)	22
MSRs [Member] \| Recurring [Member] \| Level 3 [Member] \| Weighted Average [Member] \| Measurement Input, Constant Prepayment Rate
Quantitative Information about Level 3 Fair Value Measurements [Abstract]
MSRs, Measurement input \| item	0.107		0.098
IRLCs [Member]
Quantitative Information about Level 3 Fair Value Measurements [Abstract]
Fair value estimate	$ 335	184	$ 100	$ 22
Valuation adjustment	$ 235	$ 162
Impaired loans [Member] \| Nonrecurring [Member] \| Minimum [Member] \| Measurement Input, Discount Rate
Quantitative Information about Level 3 Fair Value Measurements [Abstract]
Impaired loan, measurement input \| item	0.00		0.00
Impaired loans [Member] \| Nonrecurring [Member] \| Maximum [Member] \| Measurement Input, Discount Rate
Quantitative Information about Level 3 Fair Value Measurements [Abstract]
Impaired loan, measurement input \| item	0.15		0.16
Impaired loans [Member] \| Nonrecurring [Member] \| Weighted Average [Member] \| Measurement Input, Discount Rate
Quantitative Information about Level 3 Fair Value Measurements [Abstract]
Impaired loan, measurement input \| item	0.07
Impaired loans [Member] \| Nonrecurring [Member] \| Level 3 [Member]
Quantitative Information about Level 3 Fair Value Measurements [Abstract]
Fair value estimate	$ 5,577
Impaired loans [Member] \| Nonrecurring [Member] \| Carrying Value [Member]
Quantitative Information about Level 3 Fair Value Measurements [Abstract]
Fair value estimate	$ 5,577
Foreclosed real estate [Member] \| Nonrecurring [Member] \| Minimum [Member] \| Measurement Input, Discount Rate
Quantitative Information about Level 3 Fair Value Measurements [Abstract]
Real estate acquired through foreclosure, measurement input \| item	0.00
Foreclosed real estate [Member] \| Nonrecurring [Member] \| Maximum [Member] \| Measurement Input, Discount Rate
Quantitative Information about Level 3 Fair Value Measurements [Abstract]
Real estate acquired through foreclosure, measurement input \| item	0.16
Foreclosed real estate [Member] \| Nonrecurring [Member] \| Weighted Average [Member] \| Measurement Input, Discount Rate
Quantitative Information about Level 3 Fair Value Measurements [Abstract]
Real estate acquired through foreclosure, measurement input \| item	0.16
Foreclosed real estate [Member] \| Nonrecurring [Member] \| Level 3 [Member]
Quantitative Information about Level 3 Fair Value Measurements [Abstract]
Fair value estimate	$ 625
Foreclosed real estate [Member] \| Nonrecurring [Member] \| Carrying Value [Member]
Quantitative Information about Level 3 Fair Value Measurements [Abstract]
Fair value estimate	625
Market Approach [Member] \| MSRs [Member] \| Recurring [Member] \| Level 3 [Member]
Quantitative Information about Level 3 Fair Value Measurements [Abstract]
Fair value estimate	400		$ 437
Market Approach [Member] \| IRLCs [Member] \| Recurring [Member] \| Level 3 [Member]
Quantitative Information about Level 3 Fair Value Measurements [Abstract]
Fair value estimate	$ 335		$ 100
Market Approach [Member] \| IRLCs [Member] \| Recurring [Member] \| Level 3 [Member] \| Minimum [Member] \| Measurement Input, Pull Through Rate
Quantitative Information about Level 3 Fair Value Measurements [Abstract]
Interest-rate lock commitments, measurement input \| item	0.7		0.7
Market Approach [Member] \| IRLCs [Member] \| Recurring [Member] \| Level 3 [Member] \| Maximum [Member] \| Measurement Input, Pull Through Rate
Quantitative Information about Level 3 Fair Value Measurements [Abstract]
Interest-rate lock commitments, measurement input \| item	0.950		0.950
Market Approach [Member] \| IRLCs [Member] \| Recurring [Member] \| Level 3 [Member] \| Weighted Average [Member] \| Measurement Input, Pull Through Rate
Quantitative Information about Level 3 Fair Value Measurements [Abstract]
Interest-rate lock commitments, measurement input \| item	0.8		0.84