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The amount of accumulated unrealized loss on investment in available-for-sale and held-to-maturity debt securities in unrealized loss positions.

No definition available.

Name:	fxnc_AvailableforsaleAndHeldtomaturitySecuritiesContinuousUnrealizedLossPosition
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The amount of accumulated unrealized loss on investment in available-for-sale and held-to-maturity securities in continuous loss position for 12 months or longer.

No definition available.

Name:	fxnc_AvailableforsaleAndHeldtomaturitySecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss
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The fair value of investment in available-for-sale and held-to-maturity debt securities in unrealized loss positions.

No definition available.

Name:	fxnc_AvailableforsaleAndHeldtomaturitySecuritiesContinuousUnrealizedLossPositionFairValue
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The amount of accumulated unrealized loss on investment in available-for-sale and held-to-maturity securities in continuous loss position for less than 12 months

No definition available.

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Represents the aggregate fair value of investments in debt and equity securities categorized as available-for-sale and as held-to-maturity securities that have been in a continuous unrealized loss position for less than twelve months.

No definition available.

Name:	fxnc_AvailableforsaleAndHeldtomaturitySecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue
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- References

No definition available.

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Amount before tax of unrealized loss in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

No definition available.

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Amount of accumulated unrealized loss on investments in debt and equity securities classified as available-for-sale that have been in a continuous loss position for twelve months or longer.

No definition available.

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This item represents the aggregate fair value of investments in debt and equity securities in an unrealized loss position which are categorized neither as held-to-maturity nor trading securities.

No definition available.

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Amount of accumulated unrealized loss on investments in debt and equity securities classified as available-for-sale that have been in a continuous loss position for less than twelve months.

No definition available.

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This item represents the aggregate fair value of investments in debt and equity securities categorized neither as held-to-maturity nor trading securities that have been in a continuous unrealized loss position for less than twelve months.

No definition available.

Name:	us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue
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No definition available.

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- References

No definition available.

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Amount of accumulated unrealized loss on investment in debt security measured at amortized cost (held-to-maturity), in continuous loss position for 12 months or longer.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27337-111563

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 6
-Subparagraph (a)(2)
-URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27290-111563

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Amount of accumulated unrealized loss on investment in debt security measured at amortized cost (held-to-maturity), in unrealized loss position.

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Fair value of investment in debt security measured at amortized cost (held-to-maturity), in unrealized loss position.

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
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Amount of accumulated unrealized loss on investment in debt security measured at amortized cost (held-to-maturity), in continuous loss position for less than 12 months.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 6
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-URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27290-111563

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27337-111563

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Fair value of investment in debt security measured at amortized cost (held-to-maturity), in continuous unrealized loss position for less than 12 months.

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Fair value of investment in debt security measured at amortized cost (held-to-maturity), in continuous unrealized loss position for 12 months or longer.