XML 38 R27.htm IDEA: XBRL DOCUMENT
v3.7.0.1

Note 3 - Allowance for Loan Losses, Nonperforming Assets and Impaired Loans - Loans and Allowance for Loan Losses by Evaluation Method (Details) - USD ($) $ in Thousands | Jun. 30, 2017 | Dec. 31, 2016 | Jun. 30, 2016 | Dec. 31, 2015
--- | --- | --- | --- | ---
Collectively evaluated for impairment | $ 8,349 | $ 8,274 |  |
Total | 8,372 | 8,300 | $ 8,195 | $ 8,297
Individually evaluated for impairment | 23 | 26 |  |
Individually evaluated for impairment | 10,200 | 9,173 |  |
Collectively evaluated for impairment | 645,192 | 639,373 |  |
Total | 655,392 | 648,546 |  |
Real Estate Construction Portfolio Segment[Member] |  |  |  |
Collectively evaluated for impairment | 351 | 438 |  |
Total | 351 | 438 | 515 | 576
Individually evaluated for impairment | 0 | 0 |  |
Individually evaluated for impairment | 3,300 | 270 |  |
Collectively evaluated for impairment | 31,267 | 36,075 |  |
Total | 34,567 | 36,345 |  |
Consumer Real Estate Portfolio Segment [Member] |  |  |  |
Collectively evaluated for impairment | 2,011 | 1,805 |  |
Total | 2,033 | 1,830 | 1,776 | 1,866
Individually evaluated for impairment | 22 | 25 |  |
Individually evaluated for impairment | 1,115 | 877 |  |
Collectively evaluated for impairment | 161,253 | 156,841 |  |
Total | 162,368 | 157,718 |  |
Commercial Real Estate Portfolio Segment [Member] |  |  |  |
Collectively evaluated for impairment | 3,767 | 3,737 |  |
Total | 3,768 | 3,738 | 3,469 | 4,109
Individually evaluated for impairment | 1 | 1 |  |
Individually evaluated for impairment | 5,646 | 7,782 |  |
Collectively evaluated for impairment | 326,067 | 328,675 |  |
Total | 331,713 | 336,457 |  |
Commercial Non Real Estate Segment [Member] |  |  |  |
Collectively evaluated for impairment | 1,103 | 1,063 |  |
Total | 1,103 | 1,063 | 1,485 | 655
Individually evaluated for impairment | 0 | 0 |  |
Individually evaluated for impairment | 137 | 241 |  |
Collectively evaluated for impairment | 43,402 | 38,783 |  |
Total | 43,539 | 39,024 |  |
Public Sector and IDA Portfolio Segment[Member] |  |  |  |
Collectively evaluated for impairment | 413 | 330 |  |
Total | 413 | 330 | 381 | 436
Individually evaluated for impairment | 0 | 0 |  |
Individually evaluated for impairment | 0 | 0 |  |
Collectively evaluated for impairment | 49,533 | 45,474 |  |
Total | 49,533 | 45,474 |  |
Consumer Non Real Estate Portfolio Segment [Member] |  |  |  |
Collectively evaluated for impairment | 697 | 644 |  |
Total | 697 | 644 | 555 | 627
Individually evaluated for impairment | 0 | 0 |  |
Individually evaluated for impairment | 2 | 3 |  |
Collectively evaluated for impairment | 33,670 | 33,525 |  |
Total | 33,672 | 33,528 |  |
Unallocated Financing Receivables [Member] |  |  |  |
Collectively evaluated for impairment | 7 | 257 |  |
Total | 7 | 257 | $ 14 | $ 28
Individually evaluated for impairment | 0 | 0 |  |
Individually evaluated for impairment | 0 | 0 |  |
Collectively evaluated for impairment | 0 | 0 |  |
Total |  | $ 0 |  |

X
- Definition The valuation allowance for financing receivables that are expected to be uncollectible that were collectively evaluated for impairment. + 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 (g) -URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953423-111524 + Details
Name: | us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of valuation allowance for financing receivables that are expected to be uncollectible that were individually evaluated for impairment. + 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 (g) -URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953423-111524 + Details
Name: | us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The balance of financing receivables that were collectively evaluated for impairment. + 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 (h) -URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953423-111524 + Details
Name: | us-gaap_FinancingReceivableCollectivelyEvaluatedForImpairment
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition The balance of financing receivables that were individually evaluated for impairment. + 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 (h) -URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953423-111524 + Details
Name: | us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- 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 310 -SubTopic 10 -Section 50 -Paragraph 11B -Subparagraph (g) -URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953423-111524 Reference 2: 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=84173941&loc=SL6953423-111524 Reference 3: 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 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section S99 -Paragraph 4 -Subparagraph (SAB Topic 6.L.1) -URI http://asc.fasb.org/extlink&oid=27010918&loc=d3e74567-122707 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=82894903&loc=d3e15032-111544 + Details
Name: | us-gaap_LoansAndLeasesReceivableAllowance
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount before allowance of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes 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 310 -SubTopic 10 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=82891408&loc=d3e4428-111522 + Details
Name: | us-gaap_LoansAndLeasesReceivableGrossCarryingAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Details
Name: | us-gaap_FinancingReceivablePortfolioSegmentAxis=nksh_RealEstateConstructionPortfolioSegmentMember
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_FinancingReceivablePortfolioSegmentAxis=us-gaap_CommercialRealEstatePortfolioSegmentMember
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_FinancingReceivablePortfolioSegmentAxis=nksh_PublicSectorAndIdaPortfolioSegmentMember
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_FinancingReceivablePortfolioSegmentAxis=us-gaap_UnallocatedFinancingReceivablesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |