XML 44 R33.htm IDEA: XBRL DOCUMENT
v3.7.0.1

Note 3 - Allowance for Loan Losses, Nonperforming Assets and Impaired Loans - Past Due and Nonaccrual Loans (Details) - USD ($) $ in Thousands | Mar. 31, 2017 | Dec. 31, 2016 | Mar. 31, 2016
--- | --- | --- | ---
Loans past due 90 days or more and still accruing |  | $ 63 | [1] | $ 63 | $ 328
Nonaccruals (including impaired nonaccruals) |  | 5,680 | [1] | 5,855 | $ 6,405
Real Estate Construction Portfolio Segment[Member] | Construction Residential [Member] |  |  |  |  |
Loans past due 90 days or more and still accruing |  | 0 | [1] | 0 |
Nonaccruals (including impaired nonaccruals) |  | 266 | [1] | 270 |
Real Estate Construction Portfolio Segment[Member] | Construction Other [Member] |  |  |  |  |
Loans past due 90 days or more and still accruing |  |  |  | 0 |
Nonaccruals (including impaired nonaccruals) |  |  |  | 0 |
Consumer Real Estate Portfolio Segment [Member] | Equity Lines [Member] |  |  |  |  |
Loans past due 90 days or more and still accruing |  | 0 | [1] | 0 |
Nonaccruals (including impaired nonaccruals) |  | 0 | [1] | 0 |
Consumer Real Estate Portfolio Segment [Member] | Closed End First Liens [Member] |  |  |  |  |
Loans past due 90 days or more and still accruing |  | 6 | [1] | 6 |
Nonaccruals (including impaired nonaccruals) |  | 0 | [1] |  |
Consumer Real Estate Portfolio Segment [Member] | Closed End Junior Liens [Member] |  |  |  |  |
Loans past due 90 days or more and still accruing |  | 36 | [1] | 36 |
Nonaccruals (including impaired nonaccruals) |  | 0 | [1] | 0 |
Consumer Real Estate Portfolio Segment [Member] | Investor Owned Residential Real Estate [Member] |  |  |  |  |
Loans past due 90 days or more and still accruing |  | 0 | [1] | 0 |
Nonaccruals (including impaired nonaccruals) |  | 242 | [1] | 253 |
Commercial Real Estate Portfolio Segment [Member] | Multifamily Real Estate [Member] |  |  |  |  |
Loans past due 90 days or more and still accruing |  | 0 | [1] | 0 |
Nonaccruals (including impaired nonaccruals) |  | 1,091 | [1] | 1,091 |
Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate, Owner Occupied [Member] |  |  |  |  |
Loans past due 90 days or more and still accruing |  | 0 | [1] | 0 |
Nonaccruals (including impaired nonaccruals) |  | 1,178 | [1] | 1,183 |
Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate Other [Member] |  |  |  |  |
Loans past due 90 days or more and still accruing |  | 0 | [1] | 0 |
Nonaccruals (including impaired nonaccruals) |  | 2,695 | [1] | 2,814 |
Commercial Non Real Estate Segment [Member] | Commercial and Industrial [Member] |  |  |  |  |
Loans past due 90 days or more and still accruing | [1] | 1 |  |  |
Nonaccruals (including impaired nonaccruals) | [1] | 205 |  |  |
Commercial Portfolio Segment [Member] | Commercial and Industrial [Member] |  |  |  |  |
Loans past due 90 days or more and still accruing |  |  |  | 0 |
Nonaccruals (including impaired nonaccruals) |  |  |  | 241 |
Consumer Non Real Estate Portfolio Segment [Member] | Credit Card Receivable [Member] |  |  |  |  |
Loans past due 90 days or more and still accruing |  | 1 | [1] | 5 |
Nonaccruals (including impaired nonaccruals) |  | 0 | [1] | 0 |
Consumer Non Real Estate Portfolio Segment [Member] | Automobile Loan [Member] |  |  |  |  |
Loans past due 90 days or more and still accruing |  | 15 | [1] | 12 |
Nonaccruals (including impaired nonaccruals) |  | 3 | [1] | 3 |
Consumer Non Real Estate Portfolio Segment [Member] | Other Consumer Loans [Member] |  |  |  |  |
Loans past due 90 days or more and still accruing |  | 4 | [1] | 4 |
Nonaccruals (including impaired nonaccruals) |  | 0 | [1] | 0 |
Public Sector and IDA Portfolio Segment[Member] |  |  |  |  |
Loans past due 90 days or more and still accruing |  |  |  | 0 |
Nonaccruals (including impaired nonaccruals) |  |  |  | 0 |
Financing Receivables 30 to 89 Days Past Due [Member] |  |  |  |  |
Past due loans |  | 2,158 | [1] | 2,553 |
Financing Receivables 30 to 89 Days Past Due [Member] | Real Estate Construction Portfolio Segment[Member] | Construction Residential [Member] |  |  |  |  |
Past due loans |  | 0 | [1] | 0 |
Financing Receivables 30 to 89 Days Past Due [Member] | Real Estate Construction Portfolio Segment[Member] | Construction Other [Member] |  |  |  |  |
Past due loans |  |  |  | 25 |
Financing Receivables 30 to 89 Days Past Due [Member] | Consumer Real Estate Portfolio Segment [Member] | Equity Lines [Member] |  |  |  |  |
Past due loans |  | 73 | [1] | 10 |
Financing Receivables 30 to 89 Days Past Due [Member] | Consumer Real Estate Portfolio Segment [Member] | Closed End First Liens [Member] |  |  |  |  |
Past due loans |  | 1,197 | [1] | 1,498 |
Financing Receivables 30 to 89 Days Past Due [Member] | Consumer Real Estate Portfolio Segment [Member] | Closed End Junior Liens [Member] |  |  |  |  |
Past due loans |  | 218 | [1] | 114 |
Financing Receivables 30 to 89 Days Past Due [Member] | Consumer Real Estate Portfolio Segment [Member] | Investor Owned Residential Real Estate [Member] |  |  |  |  |
Past due loans |  |  | [1] | 56 |
Financing Receivables 30 to 89 Days Past Due [Member] | Commercial Real Estate Portfolio Segment [Member] | Multifamily Real Estate [Member] |  |  |  |  |
Past due loans |  |  | [1] | 132 |
Financing Receivables 30 to 89 Days Past Due [Member] | Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate, Owner Occupied [Member] |  |  |  |  |
Past due loans |  | 270 | [1] | 339 |
Financing Receivables 30 to 89 Days Past Due [Member] | Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate Other [Member] |  |  |  |  |
Past due loans |  | 0 | [1] | 0 |
Financing Receivables 30 to 89 Days Past Due [Member] | Commercial Non Real Estate Segment [Member] | Commercial and Industrial [Member] |  |  |  |  |
Past due loans | [1] | 36 |  |  |
Financing Receivables 30 to 89 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Commercial and Industrial [Member] |  |  |  |  |
Past due loans |  |  |  | 6 |
Financing Receivables 30 to 89 Days Past Due [Member] | Consumer Non Real Estate Portfolio Segment [Member] | Credit Card Receivable [Member] |  |  |  |  |
Past due loans |  | 10 | [1] | 8 |
Financing Receivables 30 to 89 Days Past Due [Member] | Consumer Non Real Estate Portfolio Segment [Member] | Automobile Loan [Member] |  |  |  |  |
Past due loans |  | 290 | [1] | 234 |
Financing Receivables 30 to 89 Days Past Due [Member] | Consumer Non Real Estate Portfolio Segment [Member] | Other Consumer Loans [Member] |  |  |  |  |
Past due loans |  | 64 | [1] | 131 |
Financing Receivables 30 to 89 Days Past Due [Member] | Public Sector and IDA Portfolio Segment[Member] |  |  |  |  |
Past due loans |  |  |  | 0 |
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] |  |  |  |  |
Past due loans |  | 2,759 | [1] | 1,888 |
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Real Estate Construction Portfolio Segment[Member] | Construction Residential [Member] |  |  |  |  |
Past due loans |  | 0 | [1] | 0 |
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Real Estate Construction Portfolio Segment[Member] | Construction Other [Member] |  |  |  |  |
Past due loans |  |  |  | 0 |
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Consumer Real Estate Portfolio Segment [Member] | Equity Lines [Member] |  |  |  |  |
Past due loans |  | 0 | [1] | 0 |
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Consumer Real Estate Portfolio Segment [Member] | Closed End First Liens [Member] |  |  |  |  |
Past due loans |  | 6 | [1] | 6 |
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Consumer Real Estate Portfolio Segment [Member] | Closed End Junior Liens [Member] |  |  |  |  |
Past due loans |  | 36 | [1] | 36 |
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Consumer Real Estate Portfolio Segment [Member] | Investor Owned Residential Real Estate [Member] |  |  |  |  |
Past due loans |  | 242 | [1] | 234 |
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Commercial Real Estate Portfolio Segment [Member] | Multifamily Real Estate [Member] |  |  |  |  |
Past due loans |  | 1,091 | [1] | 1,091 |
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate, Owner Occupied [Member] |  |  |  |  |
Past due loans |  | 1,178 | [1] | 202 |
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate Other [Member] |  |  |  |  |
Past due loans |  | 0 | [1] | 80 |
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Commercial Non Real Estate Segment [Member] | Commercial and Industrial [Member] |  |  |  |  |
Past due loans | [1] | 186 |  |  |
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Commercial and Industrial [Member] |  |  |  |  |
Past due loans |  |  |  | 218 |
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Consumer Non Real Estate Portfolio Segment [Member] | Credit Card Receivable [Member] |  |  |  |  |
Past due loans |  | 1 | [1] | 5 |
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Consumer Non Real Estate Portfolio Segment [Member] | Automobile Loan [Member] |  |  |  |  |
Past due loans |  | 15 | [1] | 12 |
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Consumer Non Real Estate Portfolio Segment [Member] | Other Consumer Loans [Member] |  |  |  |  |
Past due loans |  | $ 4 | [1] | 4 |
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Public Sector and IDA Portfolio Segment[Member] |  |  |  |  |
Past due loans |  |  |  | $ 0 |
[1] | Only classes with past-due or nonaccrual loans are shown.

X
- Definition Recorded investment in financing receivables that are 90 days or more past due and still accruing. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 7 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5111-111524 + Details
Name: | us-gaap_FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruing
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Recorded investment in financing receivables that are on nonaccrual status as of the balance sheet date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 7 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5111-111524 + Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Recorded Investment in financing receivables that are past due at the balance sheet date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 7A -URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953401-111524 + Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentPastDue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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

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

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

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

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

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

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

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

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_CommercialPortfolioSegmentMember
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_CreditCardReceivablesMember
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: |

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

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

X
- Details
Name: | us-gaap_FinancingReceivablesPeriodPastDueAxis=nksh_FinancingReceivables30To89DaysPastDueMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivablesPeriodPastDueAxis=us-gaap_FinancingReceivablesEqualToGreaterThan90DaysPastDueMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |