XML 70 R55.htm IDEA: XBRL DOCUMENT
v3.8.0.1

Note 5 - Allowance for Loan Losses, Nonperforming Assets and Impaired Loans - Nonperforming Assets (Details) - USD ($) $ in Thousands | Dec. 31, 2017 | Dec. 31, 2016
--- | --- | ---
Nonperforming assets: |  |  |
Nonaccrual loans |  | $ 6 | $ 1,168
Restructured loans in nonaccrual |  | 2,763 | 4,687
Total nonperforming loans |  | 2,769 | 5,855
Other real estate owned, net |  | 2,817 | 3,156
Total nonperforming assets |  | $ 5,586 | $ 9,011
Ratio of nonperforming assets to loans, net of unearned income and deferred fees and costs, plus other real estate owned |  | 0.83% | 1.38%
Ratio of allowance for loan losses to nonperforming loans | [1] | 286.20% | 141.76%
[1] | The Company defines nonperforming loans as total nonaccrual and restructured loans that are nonaccrual. Loans 90 days past due and still accruing and accruing restructured loans are excluded.

X
- Definition Reflects the percentage derived from dividing the nonperforming assets by total loans net of unearned income deferred fees plus other real estate owned. + References No definition available. + Details
Name: | nksh_AssetsRatioOfNonperformingAssetsToLoansNetOfUnearnedIncomeAndDeferredFeesPlusOreo
Namespace Prefix: | nksh_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Recorded investment in non-restructured loans that are on nonaccrual status as of the balance sheet date. + References No definition available. + Details
Name: | nksh_LoanReceivableNonaccrual
Namespace Prefix: | nksh_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Refers to restructured loans in nonaccrual. + References No definition available. + Details
Name: | nksh_NonaccrualRestructuredLoans
Namespace Prefix: | nksh_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Represents financing receivables that are in nonaccrual status and other real estate owned. + References No definition available. + Details
Name: | nksh_NonperformingAssets
Namespace Prefix: | nksh_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- References No definition available. + Details
Name: | nksh_NonperformingAssetsAbstract
Namespace Prefix: | nksh_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Refers to ratio of allowance for loan losses to nonperforming loans. + References No definition available. + Details
Name: | nksh_RatioOfAllowanceForLoanLossesToNonperformingLoans
Namespace Prefix: | nksh_
Data Type: | num:percentItemType
Balance Type: | na
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 Carrying amount as of the balance sheet date of land and buildings obtained through foreclosure proceedings or defeasance in full or partial satisfaction of a debt arrangement. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 205 -SubTopic 10 -Section S99 -Paragraph 6 -Subparagraph (SX 210.5-04(c)(Schedule III)) -URI http://asc.fasb.org/extlink&oid=27047687&loc=d3e5864-122674 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 11 -URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5162-111524 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 45 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=82891408&loc=d3e4437-111522 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 970 -SubTopic 360 -Section S99 -Paragraph 1 -Subparagraph (SX 210.12-28) -URI http://asc.fasb.org/extlink&oid=6590653&loc=d3e638233-123024 + Details
Name: | us-gaap_RealEstateAcquiredThroughForeclosure
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant