Regulatory Capital Matters (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Common equity tier 1 capital ratio
Actual, Amount	$ 240,803	$ 222,892
Actual, Ratio	12.70%	12.16%
Requirement for Capital Adequacy Purposes, Amount	$ 85,293	$ 82,478
Requirement for Capital Adequacy Purposes, Ratio	4.50%	4.50%
Total risk based capital ratio
Actual, Amount	$ 257,358	$ 238,742
Actual, Ratio	13.58%	13.03%
Requirement for Capital Adequacy Purposes, Amount	$ 151,633	$ 146,628
Requirement for Capital Adequacy Purposes, Ratio	8.00%	8.00%
Tier 1 risk based capital ratio
Actual, Amount	$ 243,097	$ 225,150
Actual, Ratio	12.83%	12.28%
Requirement for Capital Adequacy Purposes, Amount	$ 113,725	$ 109,971
Requirement for Capital Adequacy Purposes, Ratio	6.00%	6.00%
Tier 1 leverage ratio
Actual, Amount	$ 243,097	$ 225,150
Actual, Ratio	10.42%	9.91%
Requirement for Capital Adequacy Purposes, Amount	$ 93,321	$ 90,900
Requirement for Capital Adequacy Purposes, Ratio	4.00%	4.00%
Farmers National Banc Corp
Common equity tier 1 capital ratio
Actual, Amount	$ 228,023	$ 210,409
Actual, Ratio	12.07%	11.51%
Requirement for Capital Adequacy Purposes, Amount	$ 85,044	$ 82,242
Requirement for Capital Adequacy Purposes, Ratio	4.50%	4.50%
To be Well Capitalized Under Prompt Corrective Action Provisions, Amount	$ 122,841	$ 118,795
To be Well Capitalized Under Prompt Corrective Action Provisions, Ratio	6.50%	6.50%
Total risk based capital ratio
Actual, Amount	$ 242,284	$ 224,001
Actual, Ratio	12.82%	12.26%
Requirement for Capital Adequacy Purposes, Amount	$ 151,189	$ 146,209
Requirement for Capital Adequacy Purposes, Ratio	8.00%	8.00%
To be Well Capitalized Under Prompt Corrective Action Provisions, Amount	$ 188,986	$ 182,761
To be Well Capitalized Under Prompt Corrective Action Provisions, Ratio	10.00%	10.00%
Tier 1 risk based capital ratio
Actual, Amount	$ 228,023	$ 210,409
Actual, Ratio	12.07%	11.51%
Requirement for Capital Adequacy Purposes, Amount	$ 113,392	$ 109,656
Requirement for Capital Adequacy Purposes, Ratio	6.00%	6.00%
To be Well Capitalized Under Prompt Corrective Action Provisions, Amount	$ 151,189	$ 146,209
To be Well Capitalized Under Prompt Corrective Action Provisions, Ratio	8.00%	8.00%
Tier 1 leverage ratio
Actual, Amount	$ 228,023	$ 210,409
Actual, Ratio	9.75%	9.32%
Requirement for Capital Adequacy Purposes, Amount	$ 93,516	$ 90,324
Requirement for Capital Adequacy Purposes, Ratio	4.00%	4.00%
To be Well Capitalized Under Prompt Corrective Action Provisions, Amount	$ 116,895	$ 112,905
To be Well Capitalized Under Prompt Corrective Action Provisions, Ratio	5.00%	5.00%

Tier one common capital.

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Tier one common capital ratio.

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Tier one common capital ratio

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Tier one common capital required for capital adequacy.

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Tier one risk based common capital required for capital adequacy to risk weighted assets.

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Tier one risk based common capital required to be well capitalized.

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Tier one common capital required to be well capitalized to risk weighted assets.

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The amount of total capital as defined in the regulations.

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The minimum amount of Total Capital required for capital adequacy purposes under the regulatory framework for prompt corrective action.

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The minimum Total risk based capital ratio (total capital divided by risk weighted assets) required for capital adequacy purposes under the regulatory framework for prompt corrective action.

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The amount of Total Capital required to be categorized as well as capitalized under the regulatory framework for prompt corrective action.

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The Total risk based capital ratio (total capital divided by risk weighted assets) required to be categorized as "well capitalized", in the regulatory framework for prompt corrective action.

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Total Capital divided by risk weighted assets as defined in the regulations.

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Tier 1 Leverage Capital as defined in the regulations. Also called Core Capital.

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The minimum amount of Tier 1 Leverage Capital required for capital adequacy purposes under the regulatory framework for prompt corrective action.

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The minimum amount of Tier 1 Leverage Capital for capital adequacy purposes divided by average assets as defined in the regulations.

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The amount of Tier 1 Leverage Capital required to be categorized as well capitalized under the regulatory framework for prompt corrective action.

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Tier 1 Leverage Capital divided by average assets as defined in the regulations.

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Tier 1 Risk Based Capital as defined in the regulations.

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The minimum Tier One Capital Ratio (Tier one capital divided by risk-weighted assets) required for capital adequacy purposes under the regulatory framework for prompt corrective action.

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The amount of Tier 1 Risk Based Capital required to be categorized as well capitalized under the regulatory framework for prompt corrective action.

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The Tier 1 capital ratio (Tier 1 capital divided by risk weighted assets) required to be categorized as "well capitalized" under the regulatory framework for prompt corrective action.

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Tier 1 capital divided by risk weighted assets as defined by regulations.

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