XML 96 R63.htm IDEA: XBRL DOCUMENT
v2.4.0.8

Note 5 - Allowance for Loan Losses, Nonperforming Assets and Impaired Loans (Details) - Troubled Debt Restructurings by Class (USD $) In Thousands, unless otherwise specified | 12 Months Ended
--- | ---
Dec. 31, 2013 | Dec. 31, 2012
Consumer Real Estate |  |  |  |
Number of Contracts | 6 |  | 10 |
Pre-Modification Outstanding Principal Balance | $ 4,401 |  | $ 1,826 |
Post-Modification Outstanding Principal Balance | 4,576 | [1] | 1,736 | [1]
Consumer Real Estate [Member] | Closed-end First Liens [Member] |  |  |  |
Consumer Real Estate |  |  |  |
Number of Contracts | 2 |  | 5 |
Pre-Modification Outstanding Principal Balance | 453 |  | 389 |
Post-Modification Outstanding Principal Balance | 525 | [1] | 348 | [1]
Consumer Real Estate [Member] | Closed-end Junior Liens [Member] |  |  |  |
Consumer Real Estate |  |  |  |
Number of Contracts | 1 |  | 1 |
Pre-Modification Outstanding Principal Balance | 262 |  | 147 |
Post-Modification Outstanding Principal Balance | 267 | [1] | 93 | [1]
Commercial Real Estate Loans [Member] | Commercial real estate, owner occupied [Member] |  |  |  |
Consumer Real Estate |  |  |  |
Number of Contracts | 1 |  | 3 |
Pre-Modification Outstanding Principal Balance | 154 |  | 890 |
Post-Modification Outstanding Principal Balance | 239 | [1] | 895 | [1]
Commercial Real Estate Loans [Member] | Commercial Real Estate, Non Owner Occupied [Member] |  |  |  |
Consumer Real Estate |  |  |  |
Number of Contracts | 1 |  |  |
Pre-Modification Outstanding Principal Balance | 3,500 |  |  |
Post-Modification Outstanding Principal Balance | 3,500 | [1] |  |
Commercial Non Real Estate [Member] | Commercial and Industrial [Member] |  |  |  |
Consumer Real Estate |  |  |  |
Number of Contracts | 1 |  | 1 |
Pre-Modification Outstanding Principal Balance | 32 |  | 400 |
Post-Modification Outstanding Principal Balance | $ 45 | [1] | $ 400 | [1]
[1] | Post-modification outstanding recorded investment considers amounts immediately following the modification. Amounts do not reflect balances at the end of the period.

X
- Details
Name: | nksh_ConsumerRealEstateAbstract000000
Namespace Prefix: | nksh_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Number of financing receivables that have been modified by troubled debt restructurings. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 33 -URI http://asc.fasb.org/extlink&oid=28368275&loc=SL6953676-111524 + Details
Name: | us-gaap_FinancingReceivableModificationsNumberOfContracts2
Namespace Prefix: | us-gaap_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Post-modification amount of investment in financing receivables modified by troubled debt restructurings. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 33 -URI http://asc.fasb.org/extlink&oid=28368275&loc=SL6953676-111524 + Details
Name: | us-gaap_FinancingReceivableModificationsPostModificationRecordedInvestment2
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Pre-modification amount of investment in financing receivables modified by troubled debt restructurings. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 33 -URI http://asc.fasb.org/extlink&oid=28368275&loc=SL6953676-111524 + Details
Name: | us-gaap_FinancingReceivableModificationsPreModificationRecordedInvestment2
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration