XML 47 R36.htm IDEA: XBRL DOCUMENT
v3.8.0.1

Note 3 - Allowance for Loan Losses, Nonperforming Assets and Impaired Loans - Past Due and Nonaccrual Loans (Details) - USD ($) $ in Thousands | Mar. 31, 2018 | Dec. 31, 2017 | Mar. 31, 2017
--- | --- | --- | ---
Loans past due 90 days or more and still accruing |  | $ 52 | [1] | $ 51 | [1] | $ 63
Nonaccruals |  | 2,764 | [1],[2] | 2,769 | [1],[2] | $ 5,680
Consumer Real Estate Portfolio Segment [Member] | Closed End First Liens [Member] |  |  |  |  |  |
Loans past due 90 days or more and still accruing | [1] |  |  | 11 |  |
Nonaccruals | [1],[2] | 142 |  | 145 |  |
Consumer Real Estate Portfolio Segment [Member] | Closed End Junior Liens [Member] |  |  |  |  |  |
Loans past due 90 days or more and still accruing | [1] | 0 |  |  |  |
Nonaccruals | [1],[2] | 0 |  | 0 |  |
Consumer Real Estate Portfolio Segment [Member] | Investor Owned Residential Real Estate [Member] |  |  |  |  |  |
Loans past due 90 days or more and still accruing | [1] | 0 |  | 0 |  |
Nonaccruals | [1],[2] | 6 |  | 6 |  |
Commercial Real Estate Portfolio Segment [Member] | Multifamily Real Estate [Member] |  |  |  |  |  |
Loans past due 90 days or more and still accruing | [1] | 0 |  | 0 |  |
Nonaccruals | [1],[2] | 0 |  |  |  |
Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate, Owner Occupied [Member] |  |  |  |  |  |
Loans past due 90 days or more and still accruing | [1] | 0 |  | 0 |  |
Nonaccruals | [1],[2] |  |  |  |  |
Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate Other [Member] |  |  |  |  |  |
Loans past due 90 days or more and still accruing | [1] | 0 |  | 0 |  |
Nonaccruals | [1],[2] | 2,602 |  | 2,602 |  |
Commercial Non Real Estate Segment [Member] | Commercial and Industrial [Member] |  |  |  |  |  |
Loans past due 90 days or more and still accruing | [1] | 20 |  |  |  |
Nonaccruals | [1],[2] | 13 |  |  |  |
Commercial Portfolio Segment [Member] | Commercial and Industrial [Member] |  |  |  |  |  |
Loans past due 90 days or more and still accruing | [1] |  |  | 0 |  |
Nonaccruals | [1],[2] |  |  | 15 |  |
Consumer Non Real Estate Portfolio Segment [Member] | Credit Card Receivable [Member] |  |  |  |  |  |
Loans past due 90 days or more and still accruing | [1] | 11 |  | 12 |  |
Nonaccruals | [1],[2] | 0 |  | 0 |  |
Consumer Non Real Estate Portfolio Segment [Member] | Automobile Loan [Member] |  |  |  |  |  |
Loans past due 90 days or more and still accruing | [1] | 1 |  | 22 |  |
Nonaccruals | [1],[2] | 1 |  | 1 |  |
Consumer Non Real Estate Portfolio Segment [Member] | Other Consumer Loans [Member] |  |  |  |  |  |
Loans past due 90 days or more and still accruing | [1] | 20 |  | 6 |  |
Nonaccruals | [1],[2] | 0 |  | 0 |  |
Financing Receivables 30 to 89 Days Past Due [Member] |  |  |  |  |  |
Loans past due and accruing | [1] | 2,502 |  | 2,263 |  |
Financing Receivables 30 to 89 Days Past Due [Member] | Consumer Real Estate Portfolio Segment [Member] | Closed End First Liens [Member] |  |  |  |  |  |
Loans past due and accruing | [1] | 780 |  | 637 |  |
Financing Receivables 30 to 89 Days Past Due [Member] | Consumer Real Estate Portfolio Segment [Member] | Closed End Junior Liens [Member] |  |  |  |  |  |
Loans past due and accruing | [1] | 168 |  | 188 |  |
Financing Receivables 30 to 89 Days Past Due [Member] | Consumer Real Estate Portfolio Segment [Member] | Investor Owned Residential Real Estate [Member] |  |  |  |  |  |
Loans past due and accruing | [1] |  |  | 66 |  |
Financing Receivables 30 to 89 Days Past Due [Member] | Commercial Real Estate Portfolio Segment [Member] | Multifamily Real Estate [Member] |  |  |  |  |  |
Loans past due and accruing | [1] | 498 |  | 303 |  |
Financing Receivables 30 to 89 Days Past Due [Member] | Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate, Owner Occupied [Member] |  |  |  |  |  |
Loans past due and accruing | [1] | 394 |  | 402 |  |
Financing Receivables 30 to 89 Days Past Due [Member] | Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate Other [Member] |  |  |  |  |  |
Loans past due and accruing | [1] | 0 |  | 0 |  |
Financing Receivables 30 to 89 Days Past Due [Member] | Commercial Non Real Estate Segment [Member] | Commercial and Industrial [Member] |  |  |  |  |  |
Loans past due and accruing | [1] | 260 |  |  |  |
Financing Receivables 30 to 89 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Commercial and Industrial [Member] |  |  |  |  |  |
Loans past due and accruing | [1] |  |  | 131 |  |
Financing Receivables 30 to 89 Days Past Due [Member] | Consumer Non Real Estate Portfolio Segment [Member] | Credit Card Receivable [Member] |  |  |  |  |  |
Loans past due and accruing | [1] | 7 |  | 7 |  |
Financing Receivables 30 to 89 Days Past Due [Member] | Consumer Non Real Estate Portfolio Segment [Member] | Automobile Loan [Member] |  |  |  |  |  |
Loans past due and accruing | [1] | 322 |  | 375 |  |
Financing Receivables 30 to 89 Days Past Due [Member] | Consumer Non Real Estate Portfolio Segment [Member] | Other Consumer Loans [Member] |  |  |  |  |  |
Loans past due and accruing | [1] | 73 |  | 154 |  |
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] |  |  |  |  |  |
Loans past due and accruing | [1] | 2,659 |  | 2,658 |  |
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Consumer Real Estate Portfolio Segment [Member] | Closed End First Liens [Member] |  |  |  |  |  |
Loans past due and accruing | [1] |  |  | 16 |  |
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Consumer Real Estate Portfolio Segment [Member] | Closed End Junior Liens [Member] |  |  |  |  |  |
Loans past due and accruing | [1] | 0 |  |  |  |
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Consumer Real Estate Portfolio Segment [Member] | Investor Owned Residential Real Estate [Member] |  |  |  |  |  |
Loans past due and accruing | [1] | 5 |  |  |  |
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Commercial Real Estate Portfolio Segment [Member] | Multifamily Real Estate [Member] |  |  |  |  |  |
Loans past due and accruing | [1] | 0 |  |  |  |
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate, Owner Occupied [Member] |  |  |  |  |  |
Loans past due and accruing | [1] | 0 |  |  |  |
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate Other [Member] |  |  |  |  |  |
Loans past due and accruing | [1] | 2,602 |  | 2,602 |  |
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Commercial Non Real Estate Segment [Member] | Commercial and Industrial [Member] |  |  |  |  |  |
Loans past due and accruing | [1] | 20 |  |  |  |
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Commercial and Industrial [Member] |  |  |  |  |  |
Loans past due and accruing | [1] |  |  |  |  |
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Consumer Non Real Estate Portfolio Segment [Member] | Credit Card Receivable [Member] |  |  |  |  |  |
Loans past due and accruing | [1] | 11 |  | 12 |  |
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Consumer Non Real Estate Portfolio Segment [Member] | Automobile Loan [Member] |  |  |  |  |  |
Loans past due and accruing | [1] | 1 |  | 22 |  |
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Consumer Non Real Estate Portfolio Segment [Member] | Other Consumer Loans [Member] |  |  |  |  |  |
Loans past due and accruing | [1] | $ 20 |  | $ 6 |  |
[1] | Only classes with past-due or nonaccrual loans are shown.
[2] | Includes current and past due loans in nonaccrual status. Includes impaired loans in nonaccrual status.

X
- Definition Recorded investment in financing receivables that are 90 days or more past due and still accruing. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -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://fasb.org/us-gaap/role/ref/legacyRef -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://fasb.org/us-gaap/role/ref/legacyRef -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_ConsumerRealEstatePortfolioSegmentMember
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_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: |