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v2.4.1.9

Note 4 - Allowance for Loan Losses, Nonperforming Assets and Impaired Loans (Details) - Allowance for Loan Losses (USD $) In Thousands, unless otherwise specified | 3 Months Ended |  |
--- | --- | --- | ---
Mar. 31, 2015 | Mar. 31, 2014 | Dec. 31, 2014 | Dec. 31, 2013
Financing Receivable, Allowance for Credit Losses [Line Items] |  |  |  |
Balance | $ 8,257 us-gaap_LoansAndLeasesReceivableAllowance | $ 8,297 us-gaap_LoansAndLeasesReceivableAllowance | $ 8,263 us-gaap_LoansAndLeasesReceivableAllowance | $ 8,227 us-gaap_LoansAndLeasesReceivableAllowance
Charge-offs | (260)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs | (191)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs |  |
Recoveries | 53 us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery | 158 us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery |  |
Provision for loan losses | 201 us-gaap_ProvisionForLoanAndLeaseLosses | 103 us-gaap_ProvisionForLoanAndLeaseLosses |  |
Real Estate Construction [Member] |  |  |  |
Financing Receivable, Allowance for Credit Losses [Line Items] |  |  |  |
Balance | 467 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nksh_RealEstateConstructionMember | 850 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nksh_RealEstateConstructionMember | 612 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nksh_RealEstateConstructionMember | 863 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nksh_RealEstateConstructionMember
Charge-offs |  | (2)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nksh_RealEstateConstructionMember |  |
Provision for loan losses | (145)us-gaap_ProvisionForLoanAndLeaseLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nksh_RealEstateConstructionMember | (11)us-gaap_ProvisionForLoanAndLeaseLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nksh_RealEstateConstructionMember |  |
Consumer Real Estate [Member] |  |  |  |
Financing Receivable, Allowance for Credit Losses [Line Items] |  |  |  |
Balance | 1,620 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nksh_ConsumerRealEstateMember | 1,814 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nksh_ConsumerRealEstateMember | 1,662 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nksh_ConsumerRealEstateMember | 1,697 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nksh_ConsumerRealEstateMember
Charge-offs | (72)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nksh_ConsumerRealEstateMember | (54)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nksh_ConsumerRealEstateMember |  |
Provision for loan losses | 30 us-gaap_ProvisionForLoanAndLeaseLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nksh_ConsumerRealEstateMember | 171 us-gaap_ProvisionForLoanAndLeaseLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nksh_ConsumerRealEstateMember |  |
Commercial Real Estate [Member] |  |  |  |
Financing Receivable, Allowance for Credit Losses [Line Items] |  |  |  |
Balance | 3,711 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nksh_CommercialRealEstateLoansMember | 3,694 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nksh_CommercialRealEstateLoansMember | 3,537 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nksh_CommercialRealEstateLoansMember | 3,685 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nksh_CommercialRealEstateLoansMember
Charge-offs | (100)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nksh_CommercialRealEstateLoansMember | (52)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nksh_CommercialRealEstateLoansMember |  |
Recoveries | 12 us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nksh_CommercialRealEstateLoansMember | 8 us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nksh_CommercialRealEstateLoansMember |  |
Provision for loan losses | 262 us-gaap_ProvisionForLoanAndLeaseLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nksh_CommercialRealEstateLoansMember | 53 us-gaap_ProvisionForLoanAndLeaseLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nksh_CommercialRealEstateLoansMember |  |
Commercial Non Real Estate [Member] |  |  |  |
Financing Receivable, Allowance for Credit Losses [Line Items] |  |  |  |
Balance | 1,416 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nksh_CommercialNonRealEstateMember | 861 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nksh_CommercialNonRealEstateMember | 1,475 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nksh_CommercialNonRealEstateMember | 989 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nksh_CommercialNonRealEstateMember
Recoveries |  | 131 us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nksh_CommercialNonRealEstateMember |  |
Provision for loan losses | (59)us-gaap_ProvisionForLoanAndLeaseLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nksh_CommercialNonRealEstateMember | (259)us-gaap_ProvisionForLoanAndLeaseLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nksh_CommercialNonRealEstateMember |  |
Public Sector and IDA [Member] |  |  |  |
Financing Receivable, Allowance for Credit Losses [Line Items] |  |  |  |
Balance | 433 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nksh_PublicSectorAndIdaMember | 202 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nksh_PublicSectorAndIdaMember | 327 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nksh_PublicSectorAndIdaMember | 132 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nksh_PublicSectorAndIdaMember
Provision for loan losses | 106 us-gaap_ProvisionForLoanAndLeaseLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nksh_PublicSectorAndIdaMember | 70 us-gaap_ProvisionForLoanAndLeaseLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nksh_PublicSectorAndIdaMember |  |
Consumer Non Real Estate [Member] |  |  |  |
Financing Receivable, Allowance for Credit Losses [Line Items] |  |  |  |
Balance | 576 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nksh_ConsumerNonRealEstateMember | 529 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nksh_ConsumerNonRealEstateMember | 602 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nksh_ConsumerNonRealEstateMember | 576 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nksh_ConsumerNonRealEstateMember
Charge-offs | (88)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nksh_ConsumerNonRealEstateMember | (83)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nksh_ConsumerNonRealEstateMember |  |
Recoveries | 41 us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nksh_ConsumerNonRealEstateMember | 19 us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nksh_ConsumerNonRealEstateMember |  |
Provision for loan losses | 21 us-gaap_ProvisionForLoanAndLeaseLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nksh_ConsumerNonRealEstateMember | 17 us-gaap_ProvisionForLoanAndLeaseLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nksh_ConsumerNonRealEstateMember |  |
Unallocated [Member] |  |  |  |
Financing Receivable, Allowance for Credit Losses [Line Items] |  |  |  |
Balance | 34 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nksh_UnallocatedMember | 347 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nksh_UnallocatedMember | 48 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nksh_UnallocatedMember | 285 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nksh_UnallocatedMember
Provision for loan losses | $ (14)us-gaap_ProvisionForLoanAndLeaseLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nksh_UnallocatedMember | $ 62 us-gaap_ProvisionForLoanAndLeaseLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nksh_UnallocatedMember |  |

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- Definition Amount of recovery of financing receivables doubtful of collection that were previously charged off. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 11B -Subparagraph (c)(4) -URI http://asc.fasb.org/extlink&oid=35738203&loc=SL6953423-111524 + Details
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- Definition Amount of direct write-downs of financing receivables charged against the allowance. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 11B -Subparagraph (c)(3) -URI http://asc.fasb.org/extlink&oid=35738203&loc=SL6953423-111524 + Details
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- Definition Amount of allowance to cover probable credit losses on loans and leases. Includes carryover of or adjustments to the allowance for loan losses in connection with business combinations. Excludes allowance for loans and leases covered under loss sharing agreements. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03.7(d)) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 7 -Subparagraph d -Article 9 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 11B -Subparagraph (g) -URI http://asc.fasb.org/extlink&oid=35738203&loc=SL6953423-111524 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 11B -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=35738203&loc=SL6953423-111524 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 30 -Section 50 -Paragraph 2 -Subparagraph (b)(1)(ii) -URI http://asc.fasb.org/extlink&oid=6379141&loc=d3e15032-111544 Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Staff Accounting Bulletin (SAB) -Number Topic 6 -Section L -Subsection 1 + Details
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