XML 47 R37.htm IDEA: XBRL DOCUMENT
v3.23.2

Note 2 - Loans and Allowance for Credit Losses - Impaired Loans, Average Investment and Interest Income (Details) $ in Thousands | 6 Months Ended
--- | ---
Jun. 30, 2022 USD ($)
Average recorded investment | $ 5,820 | [1]
Interest income recognized | 43 |
Investor Owned Residential Real Estate [Member] | Consumer Real Estate Portfolio Segment [Member] |  |
Average recorded investment | 189 | [1]
Interest income recognized | 6 |
Commercial Real Estate, Owner Occupied [Member] | Commercial Real Estate Portfolio Segment [Member] |  |
Average recorded investment | 2,626 | [1]
Interest income recognized | 3 |
Commercial Real Estate Other [Member] | Commercial Real Estate Portfolio Segment [Member] |  |
Average recorded investment | 2,719 |
Interest income recognized | 34 |
Commercial and Industrial [Member] | Commercial Non Real Estate Segment [Member] |  |
Average recorded investment | 286 | [1]
Interest income recognized | $ 0 |
[1] | Recorded investment is net of charge-offs and interest paid while a loan is in nonaccrual status.

X
- Definition Average amount of investment of impaired financing receivables with related allowance for credit losses and without a related allowance for credit losses. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 15 -Subparagraph (c)(1) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481962/310-10-50-15 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 17 -Publisher FASB -URI https://asc.fasb.org//1943274/2147481962/310-10-50-17 + Details
Name: | us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of interest income recognized that the financing receivables (with related allowance for credit losses and without a related allowance for credit losses) were impaired. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 15 -Subparagraph (c)(2) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481962/310-10-50-15 + Details
Name: | us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=nksh_InvestorOwnedResidentialRealEstateMember
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_CommercialRealEstateOwnerOccupiedMember
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_CommercialAndIndustrialMember
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: |