Reflects the amount of troubled restructured debt not performing to modified status and non accruing.

No definition available.

Name:	nvsl_FinancingReceivableModificationsSubsequentDefaultNonAccrualStatus
Namespace Prefix:	nvsl_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Reflects the total amount of non performing assets

+ References

No definition available.

+ Details

Name:	nvsl_NonPerformingAssets
Namespace Prefix:	nvsl_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Reflects the total amount of non performing loans

+ References

No definition available.

+ Details

Name:	nvsl_NonPerformingLoans
Namespace Prefix:	nvsl_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Reflects the percentage of transfers the non performing assets to the total assets in the reporting period.

+ References

No definition available.

+ Details

Name:	nvsl_PercentageOfNonperformingAssetsToTotalAssets
Namespace Prefix:	nvsl_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Reflects the percentage of transfers the non performing assets to the net total assets in the reporting period.

+ References

No definition available.

+ Details

Name:	nvsl_PercentageOfNonperformingAssetsToTotalAssetsNet
Namespace Prefix:	nvsl_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Reflects the percentage of transfers the non performing loans to the total assets in the reporting period.

+ References

No definition available.

+ Details

Name:	nvsl_PercentageOfNonperformingLoansToTotalAssets
Namespace Prefix:	nvsl_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Details

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

- Definition

Recorded investment in financing receivables that are on nonaccrual status as of the balance sheet date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 7

-Subparagraph (d)

-URI http://asc.fasb.org/extlink&oid=35738203&loc=d3e5111-111524

+ Details

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

- Definition

Carrying amount as of the balance sheet date of all assets obtained in full or partial satisfaction of a debt arrangement through foreclosure proceedings or defeasance; includes real and personal property; equity interests in corporations, partnerships, and joint ventures; and beneficial interests in trusts.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 45

-Paragraph 3

-URI http://asc.fasb.org/extlink&oid=28367877&loc=d3e4437-111522

+ Details

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

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_CommercialLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_ConsumerLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MortgageLoansOnRealEstateLoanTypeAxis=nvsl_ConstructionAndLandDevelopmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MortgageLoansOnRealEstateLoanTypeAxis=nvsl_MultiFamilyAndCommercialRealEstateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MortgageLoansOnRealEstateLoanTypeAxis=nvsl_OneToFourFamilyMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

LOANS RECEIVABLE (Details 3) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014	Mar. 31, 2014	Dec. 31, 2013
Financing Receivable, Impaired [Line Items]
Nonaccrual loans	$ 3,601	$ 3,506
Troubled debt restructurings	1,684	1,600
Total nonperforming loans	5,285nvsl_NonPerformingLoans	5,106nvsl_NonPerformingLoans
Foreclosed real estate & other repossessed assets	100us-gaap_ForeclosedAssets	335us-gaap_ForeclosedAssets	1,114us-gaap_ForeclosedAssets	1,846us-gaap_ForeclosedAssets
Total nonperforming assets	5,385nvsl_NonPerformingAssets	5,441nvsl_NonPerformingAssets
Total nonperforming loans to total loans	1.41%	1.38%
Total nonperforming loans to total assets	1.04%	1.03%
Total nonperforming assets to total assets	1.06%	1.10%
Commercial Business Loans [Member]
Financing Receivable, Impaired [Line Items]
Nonaccrual loans	756	804
Consumer Loan [Member]
Financing Receivable, Impaired [Line Items]
Nonaccrual loans	187	187
One To Four Family [Member]
Financing Receivable, Impaired [Line Items]
Nonaccrual loans	1,644	1,414
Multi Family and Commercial Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Nonaccrual loans	371	375
Construction and Land Development [Member]
Financing Receivable, Impaired [Line Items]
Nonaccrual loans	$ 643	$ 726