LOANS RECEIVABLE (Details 7) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Mar. 31, 2014
Financing Receivable, Modifications [Line Items]
Number of Loans	5
Pre-Modification Recorded Investment	$ 248
Post-Modification Recorded Investment	248
Percentage Of Reduced Interest Rate	100.00%nvsl_PercentageOfReducedInterestRate
Extended Payment Terms [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans	1
Pre-Modification Recorded Investment	98
Post-Modification Recorded Investment	98
Percentage Of Reduced Interest Rate	39.50%
Below Market Interest Rate [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans	3
Pre-Modification Recorded Investment	30
Post-Modification Recorded Investment	30
Percentage Of Reduced Interest Rate	12.10%
Commercial Business Loans [Member] \| Extended Payment Terms [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans	1
Pre-Modification Recorded Investment	98
Post-Modification Recorded Investment	98
Percentage Of Reduced Interest Rate	39.50%
Commercial Business Loans [Member] \| Below Market Interest Rate [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans	3
Pre-Modification Recorded Investment	30
Post-Modification Recorded Investment	30
Percentage Of Reduced Interest Rate	12.10%
Real Estate [Member] \| Deferred Principal Payments [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans	1
Pre-Modification Recorded Investment	120
Post-Modification Recorded Investment	120
Percentage Of Reduced Interest Rate	48.40%
Real Estate [Member] \| One to four family [Member] \| Deferred Principal Payments [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans	1
Pre-Modification Recorded Investment	120
Post-Modification Recorded Investment	$ 120
Percentage Of Reduced Interest Rate	48.40%

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- Details

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- Definition

Number of financing receivables that have been modified by troubled debt restructurings.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 33

-URI http://asc.fasb.org/extlink&oid=35738203&loc=SL6953676-111524

+ Details

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- Definition

Post-modification amount of investment in financing receivables modified by troubled debt restructurings.

+ References

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- Definition

Pre-modification amount of investment in financing receivables modified by troubled debt restructurings.

+ References

+ Details

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