OTHER BORROWED FUNDS (Details Textual) (USD $) In Millions, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Schedule of debt disclosure [Line Items]
Federal Reserve Bank Held For Reserve Requirement	$ 2.4
Federal Reserve Bank Stock	2.4us-gaap_FederalReserveBankStock
Federal Reserve Bank of Boston [Member]
Schedule of debt disclosure [Line Items]
Commercial Real Estate Loans Pledged	7.3	7.4
Bank Overdrafts [Member] \| Federal Home Loan Bank of Boston [Member]
Schedule of debt disclosure [Line Items]
Financial Instruments Owned and Pledged as Collateral, Amount Eligible to be Repledged by Counterparty	$ 1

Represents the commercial real estate loans pledged.

No definition available.

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

- Definition

Represents the amount of federal reserve bank stock restricted to meet reserve requirements.

+ References

No definition available.

+ Details

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Namespace Prefix:	nvsl_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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- Details

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- Definition

Federal Reserve Bank stock represents an equity interest in the Federal Reserve Bank. It does not have a readily determinable fair value because its ownership is restricted and it lacks a market (liquidity).

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 325

-Section 45

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6478792&loc=d3e63345-112809

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Fair value of financial instrument held by the entity for its own account (proprietary securities) for trading or investment purposes that are carried at fair value and pledged to counterparties as collateral for financing transactions where counterparty has the right to re-pledge such.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 860

-SubTopic 30

-Section 45

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6467456&loc=d3e113888-111728

+ Details

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- Details

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Namespace Prefix:
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- Details

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