Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

+ Details

Name:	nvsl_BasisOfPresentationLineItems
Namespace Prefix:	nvsl_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of liabilities to third parties under a termination, whether or not guaranteed by the government, including a cross reference to the related termination claim or claims recorded or disclosed at the latest balance sheet date.

+ References

No definition available.

+ Details

Name:	nvsl_TerminationFee
Namespace Prefix:	nvsl_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Price of a single share of a number of saleable stocks paid or offered to be paid in a business combination.

+ References

No definition available.

+ Details

Name:	us-gaap_BusinessAcquisitionSharePrice
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant

- Definition

This element represents acquisition-related costs incurred to effect a business combination which costs have been expensed during the period. Such costs include finder's fees; advisory, legal, accounting, valuation, and other professional or consulting fees; general administrative costs, including the costs of maintaining an internal acquisitions department; and may include costs of registering and issuing debt and equity securities.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 805

-SubTopic 10

-Section 25

-Paragraph 23

-URI http://asc.fasb.org/extlink&oid=34752592&loc=d3e1043-128460

+ Details

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

- Details

Name:	us-gaap_BusinessAcquisitionAxis=nvsl_LibertyBankMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

DESCRIPTION OF BUSINESS AND BASIS OF PRESENTATION (Details Textual) - USD ($)		3 Months Ended	9 Months Ended
	Jun. 03, 2015	Sep. 30, 2015	Sep. 30, 2015
Basis Of Presentation [Line Items]
Business Combination, Acquisition Related Costs		$ 335,000	$ 947,000
Business Acquisition, Share Price	$ 11.00
Liberty Bank [Member]
Basis Of Presentation [Line Items]
Termination Fee	$ 3,100,000