XML 34 R40.htm IDEA: XBRL DOCUMENT
v2.4.0.8

Note 4 - Allowance for Loan Losses, Nonperforming Assets and Impaired Loans (Details) - Troubled Debt Restructurings by Class (USD $) In Thousands, unless otherwise specified | 3 Months Ended
--- | ---
Mar. 31, 2014 | Mar. 31, 2013
Commercial Real Estate |  |
Number of Contracts | 1 | 2
Pre-Modification Outstanding Principal Balance | $ 184 | $ 3,654
Post-Modification Outstanding Principal Balance | 209 | 3,739
Commercial Real Estate Loans [Member] | Commercial real estate, owner occupied [Member] |  |
Commercial Real Estate |  |
Number of Contracts | 1 |
Pre-Modification Outstanding Principal Balance | 184 |
Post-Modification Outstanding Principal Balance | 209 |
Real Estate Construction [Member] | Construction other [Member] |  |
Commercial Real Estate |  |
Number of Contracts |  | 1
Pre-Modification Outstanding Principal Balance |  | 3,500
Post-Modification Outstanding Principal Balance |  | 3,500
Commercial Non Real Estate [Member] | Commercial and Industrial [Member] |  |
Commercial Real Estate |  |
Number of Contracts |  | 1
Pre-Modification Outstanding Principal Balance |  | 154
Post-Modification Outstanding Principal Balance |  | $ 239

X
- Details
Name: | nksh_CommercialRealEstateAbstract0000
Namespace Prefix: | nksh_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- 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=28368275&loc=SL6953676-111524 + Details
Name: | us-gaap_FinancingReceivableModificationsNumberOfContracts2
Namespace Prefix: | us-gaap_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Post-modification amount of investment in financing receivables 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=28368275&loc=SL6953676-111524 + Details
Name: | us-gaap_FinancingReceivableModificationsPostModificationRecordedInvestment2
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Pre-modification amount of investment in financing receivables 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=28368275&loc=SL6953676-111524 + Details
Name: | us-gaap_FinancingReceivableModificationsPreModificationRecordedInvestment2
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration