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v2.4.0.8

Consolidated Statements of Income (Unaudited) (Parentheticals) (USD $) In Thousands, unless otherwise specified | 3 Months Ended
--- | ---
Mar. 31, 2014 | Mar. 31, 2013
Threshold limit of time deposits, minimum | $ 100 | $ 100

X
- Definition Represents minimum threshold limit of time deposit for which interest to be recognized separately. + References No definition available. + Details
Name: | nksh_MinimumThresholdLimitOfTimeDeposits
Namespace Prefix: | nksh_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration