XML 50 R39.htm IDEA: XBRL DOCUMENT
v3.5.0.2

Note 4 - Allowance for Loan Losses, Nonperforming Assets and Impaired Loans -Troubled Debt Restructurings (Details) $ in Thousands | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2016 USD ($) | Jun. 30, 2016 | Sep. 30, 2015 | Sep. 30, 2016 USD ($) | Sep. 30, 2015 USD ($)
Commercial Non Real Estate Segment [Member] | Commercial and Industrial [Member] |  |  |  |  |
Number of contracts | 1 |  |  | 1 |
Pre-modification outstanding principal balance | $ 28 |  |  | $ 28 |
Post-modification outstanding principal balance | $ 30 |  |  | $ 30 |
Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate Other [Member] |  |  |  |  |
Number of contracts |  | 2 |  | 2 |
Pre-modification outstanding principal balance |  |  |  | $ 3,008 |
Post-modification outstanding principal balance |  |  |  | $ 3,008 |
Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate, Owner Occupied [Member] |  |  |  |  |
Number of contracts |  |  |  |  | 1
Pre-modification outstanding principal balance |  |  |  |  | $ 994
Post-modification outstanding principal balance |  |  |  |  | $ 907
Consumer Non Real Estate Portfolio Segment [Member] | Automobile Loan [Member] |  |  |  |  |
Number of contracts | 1 |  |  | 1 |
Pre-modification outstanding principal balance | $ 5 |  |  | $ 5 |
Post-modification outstanding principal balance | $ 5 |  |  | $ 5 |
Number of contracts | 2 |  | 0 | 4 | 1
Pre-modification outstanding principal balance | $ 33 |  |  | $ 3,041 | $ 994
Post-modification outstanding principal balance | $ 35 |  |  | $ 3,043 | $ 907

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=66008989&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=66008989&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=66008989&loc=SL6953676-111524 + Details
Name: | us-gaap_FinancingReceivableModificationsPreModificationRecordedInvestment2
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Details
Name: | us-gaap_FinancingReceivablePortfolioSegmentAxis=nksh_CommercialNonRealEstateSegmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=nksh_CommercialAndIndustrialMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_CommercialRealEstatePortfolioSegmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=nksh_CommercialRealEstateOtherMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=nksh_CommercialRealEstateOwnerOccupiedMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivablePortfolioSegmentAxis=nksh_ConsumerNonRealEstatePortfolioSegmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_AutomobileLoanMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |