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=117815213&loc=d3e19207-110258

+ Details

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

- Definition

Fair value of financial and nonfinancial obligations.

+ References

+ Details

Name:	us-gaap_LiabilitiesFairValueDisclosure
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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=117815213&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, 2020 USD ($) item	Mar. 31, 2019 USD ($)	Dec. 31, 2019 USD ($) item	Dec. 31, 2018 USD ($)
MSRs [Member]
Quantitative Information about Level 3 Fair Value Measurements [Abstract]
Fair value estimate, assets	$ 240	$ 400	$ 323	$ 437
Valuation adjustment	$ (83)	(37)
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	0.167		0.111
IRLCs [Member]
Quantitative Information about Level 3 Fair Value Measurements [Abstract]
Fair value estimate, assets		335	$ 179	$ 100
Fair value estimate, liabilities	$ 61
Valuation adjustment	$ (240)	$ 235
Impaired loans [Member] \| Nonrecurring [Member] \| Minimum [Member] \| Measurement Input, Discount Rate
Quantitative Information about Level 3 Fair Value Measurements [Abstract]
Impaired loan, measurement input	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	0.15		1.60
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		0.080
Impaired loans [Member] \| Nonrecurring [Member] \| Level 3 [Member]
Quantitative Information about Level 3 Fair Value Measurements [Abstract]
Fair value estimate, assets	$ 4,378		$ 4,437
Impaired loans [Member] \| Nonrecurring [Member] \| Carrying Value [Member]
Quantitative Information about Level 3 Fair Value Measurements [Abstract]
Fair value estimate, assets	$ 4,378		$ 4,437
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	0		0
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	0.17		16
Foreclosed real estate [Member] \| Nonrecurring [Member] \| Weighted Average [Member] \| Measurement Input, Discount Rate
Quantitative Information about Level 3 Fair Value Measurements [Abstract]
Impaired loan, measurement input \| item			10
Real estate acquired through foreclosure, measurement input \| item	17.00
Foreclosed real estate [Member] \| Nonrecurring [Member] \| Level 3 [Member]
Quantitative Information about Level 3 Fair Value Measurements [Abstract]
Fair value estimate, assets	$ 471		$ 1,174
Foreclosed real estate [Member] \| Nonrecurring [Member] \| Carrying Value [Member]
Quantitative Information about Level 3 Fair Value Measurements [Abstract]
Fair value estimate, assets	471		1,174
Market Approach [Member] \| MSRs [Member] \| Recurring [Member] \| Level 3 [Member]
Quantitative Information about Level 3 Fair Value Measurements [Abstract]
Fair value estimate, assets	240		323
Market Approach [Member] \| IRLCs [Member] \| Recurring [Member] \| Level 3 [Member]
Quantitative Information about Level 3 Fair Value Measurements [Abstract]
Fair value estimate, assets			$ 179
Fair value estimate, liabilities	$ 61
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	0.87		0.83