FINANCIAL INSTRUMENTS WITH OFF-BALANCE-SHEET RISK (Details) (USD $) In Thousands, unless otherwise specified	9 Months Ended	12 Months Ended
Sep. 30, 2013	Dec. 31, 2012
Commitments to extend credit:
Commercial loan commitments	$ 9,171	$ 4,327
Unused home equity lines of credit	18,972	21,434
Commercial and industrial loan commitments	11,765	13,134
Amountsdueonothercommitment	8,075	20,790
Commercial letters of credit	$ 2,152	$ 3,964

It represents the loan commitments accounted for as derivatives, including the methods and assumptions used to estimate fair value and any associated hedging strategies.

No definition available.

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