XML 33 R40.htm IDEA: XBRL DOCUMENT v3.3.0.814

Note 5 - Securities (Details) $ in Thousands	Sep. 30, 2015 USD ($)	Dec. 31, 2014 USD ($)
Note 5 - Securities (Details) [Line Items]
Number of Temporarily Impaired Securities	210
Available-for-sale and Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value	$ 187,315
Continuous Unrealized Loss Position, Aggregate Losses	$ 6,147
Number of Temporarily Impaired Securities, Greater Than Twelve Months	110
Continuous Unrealized Loss Position, Twelve Months Or Longer, Fair Value	$ 99,981	$ 178,042
Continuous Unrealized Loss Position, 12 Months Or Longer, Aggregate Losses	$ 4,074	5,490
US Government Agencies Debt Securities [Member]
Note 5 - Securities (Details) [Line Items]
Number of Temporarily Impaired Securities	157
Available-for-sale and Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value	$ 152,434
Continuous Unrealized Loss Position, Aggregate Losses	4,773
Continuous Unrealized Loss Position, Twelve Months Or Longer, Fair Value	89,871	156,149
Continuous Unrealized Loss Position, 12 Months Or Longer, Aggregate Losses	$ 3,415	4,709
US States and Political Subdivisions Debt Securities [Member]
Note 5 - Securities (Details) [Line Items]
Number of Temporarily Impaired Securities	45
Available-for-sale and Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value	$ 29,577
Continuous Unrealized Loss Position, Aggregate Losses	1,020
Continuous Unrealized Loss Position, Twelve Months Or Longer, Fair Value	9,774	19,818
Continuous Unrealized Loss Position, 12 Months Or Longer, Aggregate Losses	$ 605	692
Corporate Debt Securities [Member]
Note 5 - Securities (Details) [Line Items]
Number of Temporarily Impaired Securities	7
Available-for-sale and Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value	$ 5,168
Continuous Unrealized Loss Position, Aggregate Losses	301
Continuous Unrealized Loss Position, Twelve Months Or Longer, Fair Value	200	1,948
Continuous Unrealized Loss Position, 12 Months Or Longer, Aggregate Losses	$ 1	27
Other Securities [Member]
Note 5 - Securities (Details) [Line Items]
Number of Temporarily Impaired Securities	1
Available-for-sale and Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value	$ 136
Continuous Unrealized Loss Position, Aggregate Losses	53
Restricted Stock [Member]
Note 5 - Securities (Details) [Line Items]
Restricted Investments	$ 1,129	$ 1,089

X

- Definition

This item represents the aggregate fair value of investments in debt and equity securities categorized as held-to-maturity and available for sale securities that have been in a continuous unrealized loss position.

+ References

No definition available.

+ Details

Name:	nksh_AvailableForSaleAndHeldToMaturitySecuritiesContinuousUnrealizedLossPositionFairValue
Namespace Prefix:	nksh_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

Amount of the excess of amortized cost basis over fair value of securities that have been in a loss position for twelve months or longer for securities.

+ References

No definition available.

+ Details

Name:	nksh_ContinuousUnrealizedLossPosition12MonthsOrLongerAggregateLosses
Namespace Prefix:	nksh_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

X

- Definition

Amount of the excess of amortized cost basis over fair value of securities that are in a loss position.

+ References

No definition available.

+ Details

Name:	nksh_ContinuousUnrealizedLossPositionAggregateLosses
Namespace Prefix:	nksh_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

X

- Definition

This item represents the aggregate fair value of investments in debt and equity securities that have been in a continuous unrealized loss position for twelve months or longer.

+ References

No definition available.

+ Details

Name:	nksh_ContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue
Namespace Prefix:	nksh_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- References

No definition available.

+ Details

Name:	nksh_Note5SecuritiesDetailsLineItems
Namespace Prefix:	nksh_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Definition

This item contains disclosure of the number of investment positions determined to be temporarily impaired.

+ References

No definition available.

+ Details

Name:	nksh_NumberOfTemporarilyImpairedSecurities
Namespace Prefix:	nksh_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

X

- Definition

This item contains disclosure of the number of investment positions determined to be temporarily impaired in a continuous loss position for twelve months or more.

+ References

No definition available.

+ Details

Name:	nksh_NumberOfTemporarilyImpairedSecuritiesGreaterThanTwelveMonths
Namespace Prefix:	nksh_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

X

- Definition

Investments which are not defined as or included in marketable (debt, equity, or other) securities whose use is restricted in whole or in part, generally by contractual agreements or regulatory requirements. For use in an unclassified balance sheet.

+ References

No definition available.

+ Details

Name:	us-gaap_RestrictedInvestments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Details

Name:	us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=us-gaap_USGovernmentAgenciesDebtSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=us-gaap_USStatesAndPoliticalSubdivisionsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=us-gaap_CorporateDebtSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=nksh_OtherSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_AwardTypeAxis=us-gaap_RestrictedStockMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: