XML 41 R35.htm IDEA: XBRL DOCUMENT
v2.4.0.8

Note 4 - Allowance for Loan Losses, Nonperforming Assets and Impaired Loans (Details) - Summary of Loans Past Due 90 Days or More and Impaired Loans (USD $) In Thousands, unless otherwise specified | 6 Months Ended | 12 Months Ended
--- | --- | ---
Jun. 30, 2014 | Jun. 30, 2013 | Dec. 31, 2013
Summary of Loans Past Due 90 Days or More and Impaired Loans [Abstract] |  |  |  |  |  |
Loans past due 90 days or more and still accruing | $ 266 | [1] | $ 125 |  | $ 190 | [1]
Ratio of loans past due 90 days or more and still accruing to loans, net of unearned income and deferred fees | 0.04% |  | 0.02% |  | 0.03% |
Accruing restructured loans | 6,240 |  | 6,234 |  | 6,191 |
Impaired loans: |  |  |  |  |  |
Impaired loans with no valuation allowance | 8,155 | [2] |  |  | 10,635 | [3]
Impaired loans with no valuation allowance |  |  | 15,946 |  | 10,372 |
Impaired loans with a valuation allowance | 2,989 | [2] |  |  | 2,354 | [3]
Impaired loans with a valuation allowance |  |  | 1,449 |  | 2,613 |
Total impaired loans | 11,144 |  | 17,395 |  | 12,985 |
Valuation allowance | (291) |  | (273) |  | (624) |
Impaired loans, net of allowance | 10,853 |  | 17,122 |  | 12,361 |
Average recorded investment in impaired loans(1) | 11,898 | [2],[4] | 17,889 | [2] | 16,654 | [2],[3],[4]
Interest income recognized on impaired loans, after designation as impaired | $ 191 | [4] | $ 77 |  | $ 267 | [4]
[1] | Only classes with past-due or nonaccrual loans are shown.
[2] | Recorded investment is net of charge-offs and interest paid while a loan is in nonaccrual status.
[3] | Recorded investment includes principal net of unearned interest and deferred fees and costs, and accrued interest.
[4] | Only classes with impaired loans are shown.

X
- Definition Reflects the carrying amount of loans modified in a troubled debt restructuring that are accruing interest. + References No definition available. + Details
Name: | nksh_AccruingRestructuredLoans
Namespace Prefix: | nksh_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Details
Name: | nksh_ImpairedLoansAbstract
Namespace Prefix: | nksh_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of investment of impaired financing receivables with related allowance for credit losses and without a related allowance for credit losses, net of allowance. + References No definition available. + Details
Name: | nksh_ImpairedLoansNetOfAllowance
Namespace Prefix: | nksh_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Represents ratio of loans past due 90 days or more and still accruing to loans, net of unearned income and deferred fees. + References No definition available. + Details
Name: | nksh_RatioOfLoansPastDue90DaysOrMoreAndStillAccruingToLoans
Namespace Prefix: | nksh_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Details
Name: | nksh_SummaryOfLoansPastDue90DaysOrMoreAndImpairedLoansAbstract
Namespace Prefix: | nksh_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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=35738203&loc=d3e5111-111524 + Details
Name: | us-gaap_FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruing
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 15 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=35738203&loc=d3e5212-111524 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 17 -URI http://asc.fasb.org/extlink&oid=35738203&loc=d3e5258-111524 + 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://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 15 -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=35738203&loc=d3e5212-111524 + Details
Name: | us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition 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://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 14A -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=35738203&loc=SL6953550-111524 + Details
Name: | us-gaap_ImpairedFinancingReceivableRecordedInvestment
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of allowance for credit losses related to recorded investment. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 15 -Subparagraph (a)(3) -URI http://asc.fasb.org/extlink&oid=35738203&loc=d3e5212-111524 + Details
Name: | us-gaap_ImpairedFinancingReceivableRelatedAllowance
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of investment in impaired financing receivables for which there is no related allowance for credit losses. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 14A -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=35738203&loc=SL6953550-111524 + Details
Name: | us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of unpaid principal balance of impaired financing receivables for which there is no related allowance for credit losses. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 15 -Subparagraph (a)(4) -URI http://asc.fasb.org/extlink&oid=35738203&loc=d3e5212-111524 + Details
Name: | us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of investment in impaired financing receivables for which there is a related allowance for credit losses. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 14A -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=35738203&loc=SL6953550-111524 + Details
Name: | us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Unpaid principal balance of impaired financing receivables for which there is a related allowance for credit losses. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 15 -Subparagraph (a)(4) -URI http://asc.fasb.org/extlink&oid=35738203&loc=d3e5212-111524 + Details
Name: | us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceUnpaidPrincipalBalance
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant