Represents the amount of denominations in which debt is to be issued.

No definition available.

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Namespace Prefix:	fncb_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Represents the amount of integral multiples in which debt is to be issued.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Represents the period during which only interest is to be paid related to the debt instrument.

+ References

No definition available.

+ Details

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Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

The amount of the principal balance on a debt instrument that is payable.

+ References

No definition available.

+ Details

Name:	fncb_DebtInstrumentPrincipalAmountPayable
Namespace Prefix:	fncb_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- References

No definition available.

+ Details

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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The percentage of the principal amount outstanding that is prepaid as the result of an amendment to debt.

+ References

No definition available.

+ Details

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Namespace Prefix:	fncb_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The percent of the original principal amount of debt to be repaid.

+ References

No definition available.

+ Details

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Namespace Prefix:	fncb_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

-SubTopic 30

-Section 55

-Paragraph 8

-URI http://asc.fasb.org/extlink&oid=34725769&loc=d3e28878-108400

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

-SubTopic 30

-Section 45

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28551-108399

+ Details

Name:	us-gaap_DebtInstrumentFaceAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.22(a)(1))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.22(a)(2))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

The interest rate applicable to the portion of the carrying amount of long-term borrowings outstanding as of the balance sheet date, including current maturities, which accrues interest at a set, unchanging rate.

+ References

+ Details

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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The cash outflow from the repayment of long-term borrowing where a lender is placed in a lien position behind debt having a higher priority of repayment (senior) in case of liquidation of the entity's assets or underlying collateral.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Financing Activities

-URI http://asc.fasb.org/extlink&oid=6513228

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 15

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=56944662&loc=d3e3291-108585

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Including the current and noncurrent portions, carrying value as of the balance sheet date of subordinated debt (with initial maturities beyond one year or beyond the operating cycle if longer). Subordinated debt places a lender in a lien position behind debt having a higher priority of repayment in liquidation of the entity's assets.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.7-03.16)

-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-03.16)

-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Article 5

-Subsection 19, 20, 22

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Staff Accounting Bulletin (SAB)

-Number Topic 10

-Section F

+ Details

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Namespace Prefix:	us-gaap_
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Balance Type:	credit
Period Type:	instant

- Details

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- Details

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- Details

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- Details

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Note 7 - Borrowed Funds (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Sep. 01, 2009	Jul. 01, 2015	Feb. 01, 2015	Dec. 31, 2014
Note 7 - Borrowed Funds (Details) [Line Items]
Subordinated Debt	$ 14,000				$ 25,000
Subordinated Debt [Member]
Note 7 - Borrowed Funds (Details) [Line Items]
Debt Instrument, Maturity Date		Sep. 01, 2019
Long-term Debt, Percentage Bearing Fixed Interest, Percentage Rate		9.00%
Debt Instrument Denominations in Which Debt is to Be Issued		$ 100
Debt Instrument Integral Multiples in Which Debt is to Be Issued		$ 100
Debt Instrument Period During Which Only Interest is to Be Paid		5 years
Debt Instrument, Interest Rate, Stated Percentage	9.00%		4.50%
Percent of Principal Amount Outstanding, Pre-payment	44.00%		44.00%	44.00%
Repayments of Subordinated Debt	$ 11,000
Subordinated Debt [Member] \| Subsequent Event [Member]
Note 7 - Borrowed Funds (Details) [Line Items]
Debt Instrument, Interest Rate, Stated Percentage			4.50%
First Payment [Member] \| Subordinated Debt [Member]
Note 7 - Borrowed Funds (Details) [Line Items]
Percent of Principal Amount Outstanding, to Be Repaid	16.00%
Debt Instrument, Principal Amount Payable	$ 4,000
Second Payment [Member] \| Subordinated Debt [Member]
Note 7 - Borrowed Funds (Details) [Line Items]
Percent of Principal Amount Outstanding, to Be Repaid	20.00%
Debt Instrument, Principal Amount Payable	$ 5,000
Final Payment [Member] \| Subordinated Debt [Member]
Note 7 - Borrowed Funds (Details) [Line Items]
Percent of Principal Amount Outstanding, to Be Repaid	20.00%
Debt Instrument, Principal Amount Payable	$ 5,000
Maximum [Member] \| Subordinated Debt [Member]
Note 7 - Borrowed Funds (Details) [Line Items]
Debt Instrument, Face Amount		$ 25,000