Significant Accounting Policies (Policies)	9 Months Ended
Sep. 30, 2017
Accounting Policies [Abstract]
New Accounting Pronouncements, Policy [Policy Text Block]	Accounting Guidance to be Adopted in Future Periods ASU 2014 - 09, Revenue from Contracts with Customers (Topic 606 ): Section A, “ Summary and Amendments That Create Revenue from Contracts with Customers (Topic 606 ) and Other Assets and Deferred Costs-Contract with Customers (Subtopic 340 - 40 );” Section B, “Conforming Amendments to Other Topics and Subtopics in the Codification and Status Tables;” and Section C, “Background Information and Basis for Conclusions,” provides a robust framework for addressing revenue recognition issues, and upon its effective date, replaces almost all existing revenue recognition guidance, including industry specific guidance, in current GAAP. On August 12, 2015, the FASB issued ASU 2015 - 14, Revenue from Contracts with Customers (Topic 606 ): “Deferral of the Effective Date,” which defers the adoption of ASU 2014 - 09 until the interim and annual reporting periods beginning after December 15, 2017. The core principle of ASU 2014 - 09 is for companies to recognize revenue to depict the transfer of goods or services to customers in amounts that reflect the consideration to which FNCB expects to be entitled in exchange for those goods or services. ASU 2014 - 09 will also result in enhanced interim and annual disclosures, both qualitative and quantitative, about revenue in order to help financial statement users understand the nature, amount, timing and uncertainty of revenue and related cash flows. FNCB will adopt this guidance on January 1, 2018. The guidance allows an entity to apply the new standard either retrospectively or through a cumulative effect adjustment as of January 1, 2018. FNCB’s largest revenue stream is net interest income, which is explicitly excluded from the scope of ASU 2014 - 09. Deposit-related service charges and gains and losses on the sales of foreclosed real estate are two revenue streams that fall within the scope of ASU 2014 - 09. Management is currently cataloguing and evaluating all of FNCB’s non-interest revenue streams, including, but not limited to, deposit-related services charges and gains and losses from the sales of foreclosed real estate, using the five -step, contract-based approach to determine applicability to ASU 2014 - 09 and is reviewing current policies and practices to identify any differences with the new guidance. Management does not expect the adoption of this ASU to have a material impact on the operating results or financial position of FNCB. ASU 2016 - 02, Leases (Topic 842 ): “Leases” will require organizations that lease assets to recognize on the balance sheet the assets and liabilities for the rights and obligations created by those leases with lease terms of more than 12 months. Consistent with current GAAP, the recognition, measurement and presentation of expenses and cash flows arising from a lease by the lessee will primarily depend on its classification as a finance or operating lease. However, unlike current GAAP, which requires only capital leases to be recognized on the balance sheet, the new ASU will require both types of leases to be recognized on the balance sheet. ASU 2016 - 02 will also require disclosures to help investors and other financial statement users better understand the amount, timing and uncertainty of cash flows arising from leases. The new disclosures will include both qualitative and quantitative requirements that provide additional information about the amounts recorded in the financial statements. ASU 2016 - 02 is effective with fiscal years, and interim periods within those fiscal years, beginning after December 15, 2018 for public entities. Accordingly, FNCB will adopt this guidance on January 1, 2019, and is currently evaluating the effect this guidance may have on its operating results or financial position. ASU 2016 - 13, Financial Instruments – Credit Losses (Topic 326 ): “Measurement of Credit Losses on Financial Instruments,” replaces the current loss impairment methodology under GAAP with a methodology that reflects expected credit losses and requires consideration of a broader range of reasonable and supportable information to form credit loss estimates in an effort to provide financial statement users with more decision-useful information about the expected credit losses on financial instruments and other commitments to extend credit. Specifically, the amendments in this ASU will require a financial asset (or a group of financial assets) measured at amortized cost basis to be presented at the net amount expected to be collected. The amendments in this update affect entities holding financial assets and net investment in leases that are not accounted for at fair value through net income, including such financial assets as loans, debt securities, trade receivables, net investments in leases, off-balance-sheet credit exposures, reinsurance receivables, and any other financial assets not excluded from the scope that have the contractual right to receive cash. On June 17, 2016, the four federal financial institution regulatory agencies (the Board of Governors of the Federal Reserve System, the Federal Deposit Insurance Corporation, the National Credit Union Administration and the Office of the Comptroller of the Currency), issued a joint statement to provide information about ASU 2016 - 13 and the initial supervisory views regarding the implementation of the new standard. The joint statement applies to all banks, savings associations, credit unions and financial institution holding companies, regardless of asset size. The statement details the key elements of, and the steps necessary for, the successful transition to the new accounting standard. In addition, the statement notifies financial institutions that because the appropriate allowance levels are institution-specific amounts, the agencies will not establish benchmark targets or ranges for the change in institutions’ allowance levels upon adoption of the ASU, or for allowance levels going forward. Due to the importance of ASU 2016 - 13, the agencies encourage financial institutions to begin planning and preparing for the transition and state that senior management, under the oversight of the board of directors, should work closely with staff in their accounting, lending, credit risk management, internal audit, and information technology functions during the transition period leading up to, and well after, adoption. ASU 2016 - 13 is effective for public business entities that are U.S. Securities and Exchange Commission (“SEC”) filers for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. All entities may adopt the amendments in this ASU earlier as of the fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. Accordingly, FNCB will adopt this guidance on January 1, 2020. FNCB has created a Current Expected Credit Loss (“CECL”) task group comprised of members of its finance, credit administration, lending, internal audit, loan operations and information systems units. The CECL task group has become familiar with the provisions of ASU 2016 - 13 and is in the process of planning and preparing for the transition to the new guidance, which includes, but is not limited to: ( 1 ) developing an appropriate course of action for FNCB taking into consideration the nature, scope and risk of its lending and investing activities; ( 2 ) identifying segments and sub-segments within the loan portfolio that have similar risk characteristics; ( 3 ) reviewing the existing allowance and credit risk management practices to identify processes that may be leveraged when applying the new guidance; ( 4 ) identifying data needs and implementing changes that are necessary to its core operating system and interfaces to be able to capture data requirements; and ( 5 ) evaluating the effect this guidance may have on FNCB’s operating results and/or financial position, including assessing any potential impact on its capital. Refer to Note 2 to FNCB ’s consolidated financial statements included in the 2016 Annual Report on Form 10 -K and the Quarterly Report on Form 10 -Q for the periods ended March 31, 2017 and June 30, 2017 for a discussion of additional accounting guidance applicable to FNCB that will be adopted in future periods.

Accounting Guidance to be Adopted in Future Periods

ASU

2014

09,

Revenue from Contracts with Customers (Topic

606

): Section A, “

Summary and Amendments That Create Revenue from Contracts with Customers (Topic

606

) and Other Assets and Deferred Costs-Contract with Customers (Subtopic

340

);” Section B, “Conforming Amendments to Other Topics and Subtopics in the Codification and Status Tables;” and Section C, “Background Information and Basis for Conclusions,” provides a robust framework for addressing revenue recognition issues, and upon its effective date, replaces almost all existing revenue recognition guidance, including industry specific guidance, in current GAAP. On

August 12, 2015,

the FASB issued ASU

2015

14,

Revenue from Contracts with Customers (Topic

606

): “Deferral of the Effective Date,” which defers the adoption of ASU

2014

until the interim and annual reporting periods beginning after

December 15, 2017.

The core principle of ASU

2014

is for companies to recognize revenue to depict the transfer of goods or services to customers in amounts that reflect the consideration to which FNCB expects to be entitled in exchange for those goods or services. ASU

2014

will also result in enhanced interim and annual disclosures, both qualitative and quantitative, about revenue in order to help financial statement users understand the nature, amount, timing and uncertainty of revenue and related cash flows. FNCB will adopt this guidance on

January 1, 2018.

The guidance allows an entity to apply the new standard either retrospectively or through a cumulative effect adjustment as of

January 1, 2018.

FNCB’s largest revenue stream is net interest income, which is explicitly excluded from the scope of ASU

2014

09.

Deposit-related service charges and gains and losses on the sales of foreclosed real estate are

two

revenue streams that fall within the scope of ASU

2014

09.

Management is currently cataloguing and evaluating all of FNCB’s non-interest revenue streams, including, but

not

limited to, deposit-related services charges and gains and losses from the sales of foreclosed real estate, using the

five

-step, contract-based approach to determine applicability to ASU

2014

and is reviewing current policies and practices to identify any differences with the new guidance. Management does

not

expect the adoption of this ASU to have a material impact on the operating results or financial position of FNCB.

ASU

2016

02,

Leases (Topic

842

): “Leases” will require organizations that lease assets to recognize on the balance sheet the assets and liabilities for the rights and obligations created by those leases with lease terms of more than

months. Consistent with current GAAP, the recognition, measurement and presentation of expenses and cash flows arising from a lease by the lessee will primarily depend on its classification as a finance or operating lease. However, unlike current GAAP, which requires only capital leases to be recognized on the balance sheet, the new ASU will require both types of leases to be recognized on the balance sheet. ASU

2016

will also require disclosures to help investors and other financial statement users better understand the amount, timing and uncertainty of cash flows arising from leases. The new disclosures will include both qualitative and quantitative requirements that provide additional information about the amounts recorded in the financial statements. ASU

2016

is effective with fiscal years, and interim periods within those fiscal years, beginning after

December 15, 2018

for public entities.

Accordingly, FNCB will adopt this guidance on

January 1, 2019,

and is currently evaluating the effect this guidance

may

have on its operating results or financial position.

ASU

2016

13,

Financial Instruments

– Credit Losses (Topic

326

): “Measurement of Credit Losses on Financial Instruments,” replaces the current loss impairment methodology under GAAP with a methodology that reflects expected credit losses and requires consideration of a broader range of reasonable and supportable information to form credit loss estimates in an effort to provide financial statement users with more decision-useful information about the expected credit losses on financial instruments and other commitments to extend credit. Specifically, the amendments in this ASU will require a financial asset (or a group of financial assets) measured at amortized cost basis to be presented at the net amount expected to be collected. The amendments in this update affect entities holding financial assets and net investment in leases that are

not

accounted for at fair value through net income, including such financial assets as loans, debt securities, trade receivables, net investments in leases, off-balance-sheet credit exposures, reinsurance receivables, and any other financial assets

not

excluded from the scope that have the contractual right to receive cash. On

June 17, 2016,

the

four

federal financial institution regulatory agencies (the Board of Governors of the Federal Reserve System, the Federal Deposit Insurance Corporation, the National Credit Union Administration and the Office of the Comptroller of the Currency), issued a joint statement to provide information about ASU

2016

and the initial supervisory views regarding the implementation of the new standard. The joint statement applies to all banks, savings associations, credit unions and financial institution holding companies, regardless of asset size. The statement details the key elements of, and the steps necessary for, the successful transition to the new accounting standard. In addition, the statement notifies financial institutions that because the appropriate allowance levels are institution-specific amounts, the agencies will

not

establish benchmark targets or ranges for the change in institutions’ allowance levels upon adoption of the ASU, or for allowance levels going forward. Due to the importance of ASU

2016

13,

the agencies encourage financial institutions to begin planning and preparing for the transition and state that senior management, under the oversight of the board of directors, should work closely with staff in their accounting, lending, credit risk management, internal audit, and information technology functions during the transition period leading up to, and well after, adoption. ASU

2016

is effective for public business entities that are U.S. Securities and Exchange Commission (“SEC”) filers for fiscal years beginning after

December 15, 2019,

including interim periods within those fiscal years. All entities

may

adopt the amendments in this ASU earlier as of the fiscal years beginning after

December 15, 2018,

including interim periods within those fiscal years. Accordingly, FNCB will adopt this guidance on

January 1, 2020.

FNCB has created a Current Expected Credit Loss (“CECL”) task group comprised of members of its finance, credit administration, lending, internal audit, loan operations and information systems units. The CECL task group has become familiar with the provisions of ASU

2016

and is in the process of planning and preparing for the transition to the new guidance, which includes, but is

not

limited to: (

) developing an appropriate course of action for FNCB taking into consideration the nature, scope and risk of its lending and investing activities; (

) identifying segments and sub-segments within the loan portfolio that have similar risk characteristics; (

) reviewing the existing allowance and credit risk management practices to identify processes that

may

be leveraged when applying the new guidance; (

) identifying data needs and implementing changes that are necessary to its core operating system and interfaces to be able to capture data requirements; and (

) evaluating the effect this guidance

may

have on FNCB’s operating results and/or financial position, including assessing any potential impact on its capital.

Refer to Note

to FNCB

’s consolidated financial statements included in the

2016

Annual Report on Form

-K and the Quarterly Report on Form

-Q for the periods ended

March 31, 2017

and

June 30, 2017

for a discussion of additional accounting guidance applicable to FNCB that will be adopted in future periods.