Regulatory Capital Matters (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Common equity tier 1 capital ratio
Actual, Amount	$ 406,169	$ 392,244
Actual, Ratio	10.91%	10.61%
Requirement for Capital Adequacy Purposes, Amount	$ 167,578	$ 166,303
Requirement for Capital Adequacy Purposes, Ratio	4.50%	4.50%
Total risk based capital ratio
Actual, Amount	$ 533,935	$ 519,684
Actual, Ratio	0.1434	0.1406
Requirement for Capital Adequacy Purposes, Amount	$ 297,916	$ 295,650
Requirement for Capital Adequacy Purposes, Ratio	0.08	0.08
Tier 1 risk based capital ratio
Actual, Amount	$ 424,169	$ 410,244
Actual, Ratio	0.1139	0.111
Requirement for Capital Adequacy Purposes, Amount	$ 223,437	$ 221,737
Requirement for Capital Adequacy Purposes, Ratio	0.06	0.06
Tier 1 leverage ratio
Actual, Amount	$ 424,169	$ 410,244
Actual, Ratio	0.082	0.0802
Requirement for Capital Adequacy Purposes, Amount	$ 206,949	$ 204,598
Requirement for Capital Adequacy Purposes, Ratio	0.04	0.04
Farmers National Banc Corp
Common equity tier 1 capital ratio
Actual, Amount	$ 426,179	$ 411,304
Actual, Ratio	11.46%	11.15%
Requirement for Capital Adequacy Purposes, Amount	$ 167,368	$ 165,996
Requirement for Capital Adequacy Purposes, Ratio	4.50%	4.50%
To be Well Capitalized Under Prompt Corrective Action Provisions, Amount	$ 241,753	$ 239,772
To be Well Capitalized Under Prompt Corrective Action Provisions, Ratio	6.50%	6.50%
Total risk based capital ratio
Actual, Amount	$ 463,945	$ 447,584
Actual, Ratio	0.1247	0.1213
Requirement for Capital Adequacy Purposes, Amount	$ 297,543	$ 295,104
Requirement for Capital Adequacy Purposes, Ratio	0.08	0.08
To be Well Capitalized Under Prompt Corrective Action Provisions, Amount	$ 371,928	$ 368,881
To be Well Capitalized Under Prompt Corrective Action Provisions, Ratio	0.10	0.10
Tier 1 risk based capital ratio
Actual, Amount	$ 426,179	$ 411,304
Actual, Ratio	0.1146	0.1115
Requirement for Capital Adequacy Purposes, Amount	$ 223,157	$ 221,328
Requirement for Capital Adequacy Purposes, Ratio	0.06	0.06
To be Well Capitalized Under Prompt Corrective Action Provisions, Amount	$ 297,543	$ 295,104
To be Well Capitalized Under Prompt Corrective Action Provisions, Ratio	0.08	0.08
Tier 1 leverage ratio
Actual, Amount	$ 426,179	$ 411,304
Actual, Ratio	0.0826	0.0807
Requirement for Capital Adequacy Purposes, Amount	$ 206,383	$ 203,989
Requirement for Capital Adequacy Purposes, Ratio	0.04	0.04
To be Well Capitalized Under Prompt Corrective Action Provisions, Amount	$ 257,978	$ 254,986
To be Well Capitalized Under Prompt Corrective Action Provisions, Ratio	0.05	0.05

Tier one common capital.

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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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Amount of total capital as defined by regulatory framework.

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Amount of minimum total risk-based capital required for capital adequacy as defined by regulatory framework.

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 942
-SubTopic 505
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (c)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477270/942-505-50-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 942
-SubTopic 505
-Name Accounting Standards Codification
-Section 50
-Paragraph 1B
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477270/942-505-50-1B

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