Summary of Significant Accounting Policies	6 Months Ended
Jun. 30, 2018
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS Principles of Consolidation: Farmers National Banc Corp. (“Company”) is a Financial Holding Company registered under the Bank Holding Company Act of 1956, as amended. The Company provides full banking services through its nationally chartered subsidiary, The Farmers National Bank of Canfield (“Bank”). The Bank acquired Bowers Insurance Agency, Inc. (“Bowers”) and consolidated the activity of the Bowers with Farmers National Insurance (“Insurance”) during 2016. The Company acquired Monitor Bancorp, Inc. (“Monitor”), the holding company for Monitor Bank in August of 2017 and consolidated all activity within the Bank. Farmers National Captive, Inc. (“Captive”) was formed during the third quarter of 2016 and is a wholly-owned insurance subsidiary of the Company that provides property and casualty insurance coverage to the Company and its subsidiaries. The Captive pools resources with thirteen other similar insurance company subsidiaries of financial institutions to spread a limited amount of risk among themselves and to provide insurance where not currently available or economically feasible in today’s insurance market place. The consolidated financial statements also include the accounts of the Bank’s subsidiaries; Insurance and Farmers of Canfield Investment Co. (“Investments”). The Company provides trust services through its subsidiary, Farmers Trust Company (“Trust”), retirement consulting services through National Associates, Inc. (“NAI”) and insurance services through the Bank’s subsidiary, Insurance. The consolidated financial statements include the accounts of the Company, the Bank and its subsidiaries, along with the Trust, NAI and Captive. All significant intercompany balances and transactions have been eliminated in the consolidation. Basis of Presentation: The unaudited condensed consolidated financial statements have been prepared in conformity with the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by U.S. generally accepted accounting principles (“U.S. GAAP”) for complete financial statements. The financial statements should be read in conjunction with the consolidated financial statements and notes thereto included in the Company’s 2017 Annual Report to Shareholders included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2017. The interim consolidated financial statements include all adjustments (consisting of only normal recurring items) that, in the opinion of management, are necessary for a fair presentation of the financial position and results of operations for the periods presented. The results of operations for the interim periods disclosed herein are not necessarily indicative of the results that may be expected for a full year. Certain items included in the prior period financial statements were reclassified to conform to the current period presentation. There was no effect on net income or total stockholders’ equity. Estimates: The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates. Segments: The Company provides a broad range of financial services to individuals and companies in northeastern Ohio and western Pennsylvania. Operations are managed and financial performance is primarily aggregated and reported in three lines of business, the Bank segment, the Trust segment and the Retirement Consulting segment. Equity: The Company, with the approval of shareholders at the April 2018 annual meeting, increased the authorized shares available for issuance from 35,000,000 to 50,000,000 shares. Outstanding shares at June 30, 2018 were 27,640,921. Comprehensive Income: Comprehensive income consists of net income and other comprehensive income. Other comprehensive income consists of unrealized gains and losses on securities available for sale and changes in the funded status of the post-retirement health plan, which are recognized as separate components of stockholders equity, net of tax effects. The post-retirement health plan was eliminated during 2017 and the associated balance sheet accounts, including other comprehensive income were reduced to zero. New Accounting Standards: During April of 2017, the FASB issued ASU 2017-08, Receivables—Nonrefundable Fees and Other Costs (Subtopic 310-20): Premium Amortization on Purchased Callable Debt Securities. Under current U.S. GAAP, a premium is typically amortized to the maturity date when a callable debt security is purchased at a premium, even if the holder is certain the call will be exercised. As a result, upon the exercise of a call on a callable debt security held at a premium, the unamortized premium is recorded as a loss in earnings. The new standard shortens the amortization period for the premium to the earliest call date to more closely align interest income recorded on bonds held at a premium or a discount with the economics of the underlying instrument. The standard takes effect for public business entities for fiscal years and interim periods within those fiscal years, beginning after December 15, 2018. Early adoption is permitted, including adoption in an interim period. The Company early adopted this ASU effective January 1, 2018 and there was no material impact on its Consolidated Financial Statements. In June 2016, the FASB issued ASU 2016-13: Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments. The ASU requires an organization to measure all expected credit losses for financial assets held at the reporting date based on historical experience, current conditions, and reasonable and supportable forecasts. Financial institutions and other organizations will now use forward-looking information to better inform their credit loss estimates. Many of the loss estimation techniques applied today will still be permitted, although the inputs to those techniques will change to reflect the full amount of expected credit losses. Organizations will continue to use judgment to determine which loss estimation method is appropriate for their circumstances. Additionally, the ASU amends the accounting for credit losses on available-for-sale debt securities and purchased financial assets with credit deterioration. ASU 2016-13 is effective for public companies for annual periods beginning after December 15, 2019, including interim periods within those fiscal years. Entities will apply the standard's provisions as a cumulative-effect adjustment to retained earnings as of the beginning of the first reporting period in which the guidance is adopted. The Company has begun to accumulate historical credit information, established an internal committee and begun the installation process of new software in preparation for testing in early 2019. Adoption of ASU 2016-13 will happen on January 1, 2020. Management has not determined the full impact the new standard will have on the Consolidated Financial Statements. In January 2016, FASB issued ASU 2016-01: Financial Instruments – Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities. The main objective of ASU 2016-01 is to enhance the reporting model for financial instruments to provide users of financial statements with more decision-useful information. ASU 2016-01 addresses certain aspects of recognition, measurement, presentation, and disclosure of financial instruments. Some of the amendments in ASU 2016-01 include the following: 1) Require equity investments (except those accounted for under the equity method of accounting or those that result in consolidation of the investee) to be measured at fair value with changes in fair value recognized in net income; 2) Simplify the impairment assessment of equity investments without readily determinable fair values by requiring a qualitative assessment to identify impairment; 3) Require public business entities to use the exit price notion when measuring the fair value of financial instruments for disclosure purposes; and 4) Require an entity to present separately in other comprehensive income the portion of the total change in the fair value of a liability resulting from a change in the instrument-specific credit risk when the entity has elected to measure the liability at fair value; among others. The Company adopted ASU 2016-01 on January 1, 2018 and recorded a cumulative effect adjustment of $169 thousand increase to retained earnings and a decrease to accumulated other comprehensive income. The change in fair value for equity securities which is now recorded in net income rather than comprehensive income was not material for the three and six months ended June 30, 2018. In May 2014, FASB issued ASU 2014-09: Revenue from Contracts with Customers (Topic 606). The ASU creates a new topic, Topic 606, to provide guidance on revenue recognition for entities that enter into contracts with customers to transfer goods or services or enter into contracts for the transfer of nonfinancial assets. The core principle of the guidance is that an entity should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. Additional disclosures are required to provide quantitative and qualitative information regarding the nature, amount, timing, and uncertainty of revenue and cash flows arising from contracts with customers. The new guidance is effective for the Company’s year ending December 31, 2018 and was adopted as of January 1, 2018. Interest income is outside of the scope of the new standard and was not impacted by the adoption of the standard. An evaluation of the Company’s noninterest income streams resulted in no change in revenue recognition since adoption. Refer to the Revenue from Contracts with Customers footnote for further discussion on the Company’s accounting for revenue sources within the scope of ASC 606. The Company adopted ASC 606 using the modified retrospective method applied to all contracts not completed as of January 1, 2018. Results for reporting periods beginning after January 1, 2018 are presented under ASC 606 while prior period amounts continue to be reported in accordance with legacy GAAP. The adoption of ASC 606 did not result in a change to the accounting for any of the in-scope revenue streams; as such, no cumulative effect adjustment was recorded.

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

Principles of Consolidation:

Farmers National Banc Corp. (“Company”) is a Financial Holding Company registered under the Bank Holding Company Act of 1956, as amended. The Company provides full banking services through its nationally chartered subsidiary, The Farmers National Bank of Canfield (“Bank”). The Bank acquired Bowers Insurance Agency, Inc. (“Bowers”) and consolidated the activity of the Bowers with Farmers National Insurance (“Insurance”) during 2016. The Company acquired Monitor Bancorp, Inc. (“Monitor”), the holding company for Monitor Bank in August of 2017 and consolidated all activity within the Bank. Farmers National Captive, Inc. (“Captive”) was formed during the third quarter of 2016 and is a wholly-owned insurance subsidiary of the Company that provides property and casualty insurance coverage to the Company and its subsidiaries. The Captive pools resources with thirteen other similar insurance company subsidiaries of financial institutions to spread a limited amount of risk among themselves and to provide insurance where not currently available or economically feasible in today’s insurance market place. The consolidated financial statements also include the accounts of the Bank’s subsidiaries; Insurance and Farmers of Canfield Investment Co. (“Investments”). The Company provides trust services through its subsidiary, Farmers Trust Company (“Trust”), retirement consulting services through National Associates, Inc. (“NAI”) and insurance services through the Bank’s subsidiary, Insurance. The consolidated financial statements include the accounts of the Company, the Bank and its subsidiaries, along with the Trust, NAI and Captive. All significant intercompany balances and transactions have been eliminated in the consolidation.

Basis of Presentation:

The unaudited condensed consolidated financial statements have been prepared in conformity with the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by U.S. generally accepted accounting principles (“U.S. GAAP”) for complete financial statements. The financial statements should be read in conjunction with the consolidated financial statements and notes thereto included in the Company’s 2017 Annual Report to Shareholders included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2017. The interim consolidated financial statements include all adjustments (consisting of only normal recurring items) that, in the opinion of management, are necessary for a fair presentation of the financial position and results of operations for the periods presented. The results of operations for the interim periods disclosed herein are not necessarily indicative of the results that may be expected for a full year. Certain items included in the prior period financial statements were reclassified to conform to the current period presentation. There was no effect on net income or total stockholders’ equity.

Estimates:

The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates.

Segments:

The Company provides a broad range of financial services to individuals and companies in northeastern Ohio and western Pennsylvania. Operations are managed and financial performance is primarily aggregated and reported in three lines of business, the Bank segment, the Trust segment and the Retirement Consulting segment.

Equity:

The Company, with the approval of shareholders at the April 2018 annual meeting, increased the authorized shares available for issuance from 35,000,000 to 50,000,000 shares. Outstanding shares at June 30, 2018 were 27,640,921.

Comprehensive Income:

Comprehensive income consists of net income and other comprehensive income. Other comprehensive income consists of unrealized gains and losses on securities available for sale and changes in the funded status of the post-retirement health plan, which are recognized as separate components of stockholders equity, net of tax effects. The post-retirement health plan was eliminated during 2017 and the associated balance sheet accounts, including other comprehensive income were reduced to zero.

New Accounting Standards:

During April of 2017, the FASB issued ASU 2017-08, Receivables—Nonrefundable Fees and Other Costs (Subtopic 310-20): Premium Amortization on Purchased Callable Debt Securities. Under current U.S. GAAP, a premium is typically amortized to the maturity date when a callable debt security is purchased at a premium, even if the holder is certain the call will be exercised. As a result, upon the exercise of a call on a callable debt security held at a premium, the unamortized premium is recorded as a loss in earnings. The new standard shortens the amortization period for the premium to the earliest call date to more closely align interest income recorded on bonds held at a premium or a discount with the economics of the underlying instrument. The standard takes effect for public business entities for fiscal years and interim periods within those fiscal years, beginning after December 15, 2018. Early adoption is permitted, including adoption in an interim period. The Company early adopted this ASU effective January 1, 2018 and there was no material impact on its Consolidated Financial Statements.

In June 2016, the FASB issued ASU 2016-13: Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments. The ASU requires an organization to measure all expected credit losses for financial assets held at the reporting date based on historical experience, current conditions, and reasonable and supportable forecasts. Financial institutions and other organizations will now use forward-looking information to better inform their credit loss estimates. Many of the loss estimation techniques applied today will still be permitted, although the inputs to those techniques will change to reflect the full amount of expected credit losses. Organizations will continue to use judgment to determine which loss estimation method is appropriate for their circumstances. Additionally, the ASU amends the accounting for credit losses on available-for-sale debt securities and purchased financial assets with credit deterioration. ASU 2016-13 is effective for public companies for annual periods beginning after December 15, 2019, including interim periods within those fiscal years. Entities will apply the standard's provisions as a cumulative-effect adjustment to retained earnings as of the beginning of the first reporting period in which the guidance is adopted. The Company has begun to accumulate historical credit information, established an internal committee and begun the installation process of new software in preparation for testing in early 2019. Adoption of ASU 2016-13 will happen on January 1, 2020. Management has not determined the full impact the new standard will have on the Consolidated Financial Statements.

In January 2016, FASB issued ASU 2016-01: Financial Instruments – Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities. The main objective of ASU 2016-01 is to enhance the reporting model for financial instruments to provide users of financial statements with more decision-useful information. ASU 2016-01 addresses certain aspects of recognition, measurement, presentation, and disclosure of financial instruments. Some of the amendments in ASU 2016-01 include the following: 1) Require equity investments (except those accounted for under the equity method of accounting or those that result in consolidation of the investee) to be measured at fair value with changes in fair value recognized in net income; 2) Simplify the impairment assessment of equity investments without readily determinable fair values by requiring a qualitative assessment to identify impairment; 3) Require public business entities to use the exit price notion when measuring the fair value of financial instruments for disclosure purposes; and 4) Require an entity to present separately in other comprehensive income the portion of the total change in the fair value of a liability resulting from a change in the instrument-specific credit risk when the entity has elected to measure the liability at fair value; among others. The Company adopted ASU 2016-01 on January 1, 2018 and recorded a cumulative effect adjustment of $169 thousand increase to retained earnings and a decrease to accumulated other comprehensive income. The change in fair value for equity securities which is now recorded in net income rather than comprehensive income was not material for the three and six months ended June 30, 2018.

In May 2014, FASB issued ASU 2014-09: Revenue from Contracts with Customers (Topic 606). The ASU creates a new topic, Topic 606, to provide guidance on revenue recognition for entities that enter into contracts with customers to transfer goods or services or enter into contracts for the transfer of nonfinancial assets. The core principle of the guidance is that an entity should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. Additional disclosures are required to provide quantitative and qualitative information regarding the nature, amount, timing, and uncertainty of revenue and cash flows arising from contracts with customers. The new guidance is effective for the Company’s year ending December 31, 2018 and was adopted as of January 1, 2018. Interest income is outside of the scope of the new standard and was not impacted by the adoption of the standard. An evaluation of the Company’s noninterest income streams resulted in no change in revenue recognition since adoption. Refer to the Revenue from Contracts with Customers footnote for further discussion on the Company’s accounting for revenue sources within the scope of ASC 606.

The Company adopted ASC 606 using the modified retrospective method applied to all contracts not completed as of January 1, 2018. Results for reporting periods beginning after January 1, 2018 are presented under ASC 606 while prior period amounts continue to be reported in accordance with legacy GAAP. The adoption of ASC 606 did not result in a change to the accounting for any of the in-scope revenue streams; as such, no cumulative effect adjustment was recorded.