Regulatory Matters (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Common equity tier 1 capital ratio
Actual, Amount	$ 403,307	$ 362,950
Actual, Ratio	13.71%	13.16%
Requirement for Capital Adequacy Purposes, Amount	$ 132,349	$ 132,921
Requirement for Capital Adequacy Purposes, Ratio	4.50%	4.50%
Total risk based capital ratio
Actual, Amount	$ 523,285	$ 485,336
Actual, Ratio	0.1779	0.1760
Requirement for Capital Adequacy Purposes, Amount	$ 235,288	$ 236,303
Requirement for Capital Adequacy Purposes, Ratio	0.080	0.080
Tier 1 risk based capital ratio
Actual, Amount	$ 421,307	$ 380,950
Actual, Ratio	0.1432	0.1382
Requirement for Capital Adequacy Purposes, Amount	$ 176,466	$ 177,228
Requirement for Capital Adequacy Purposes, Ratio	0.060	0.060
Tier 1 leverage ratio
Actual, Amount	$ 421,307	$ 380,950
Actual, Ratio	0.0984	0.1012
Requirement for Capital Adequacy Purposes, Amount	$ 171,233	$ 161,179
Requirement for Capital Adequacy Purposes, Ratio	0.040	0.040
Farmers National Banc Corp
Common equity tier 1 capital ratio
Actual, Amount	$ 372,679	$ 345,065
Actual, Ratio	12.71%	12.55%
Requirement for Capital Adequacy Purposes, Amount	$ 131,968	$ 132,490
Requirement for Capital Adequacy Purposes, Ratio	4.50%	4.50%
To be Well Capitalized Under Prompt Corrective Action Provisions, Amount	$ 190,620	$ 191,374
To be Well Capitalized Under Prompt Corrective Action Provisions, Ratio	6.50%	6.50%
Total risk based capital ratio
Actual, Amount	$ 399,657	$ 374,451
Actual, Ratio	0.1362	0.1362
Requirement for Capital Adequacy Purposes, Amount	$ 234,609	$ 235,537
Requirement for Capital Adequacy Purposes, Ratio	0.080	0.080
To be Well Capitalized Under Prompt Corrective Action Provisions, Amount	$ 293,262	$ 294,421
To be Well Capitalized Under Prompt Corrective Action Provisions, Ratio	0.100	0.100
Tier 1 risk based capital ratio
Actual, Amount	$ 372,679	$ 345,065
Actual, Ratio	0.1271	0.1255
Requirement for Capital Adequacy Purposes, Amount	$ 175,957	$ 176,653
Requirement for Capital Adequacy Purposes, Ratio	0.060	0.060
To be Well Capitalized Under Prompt Corrective Action Provisions, Amount	$ 234,609	$ 235,537
To be Well Capitalized Under Prompt Corrective Action Provisions, Ratio	0.080	0.080
Tier 1 leverage ratio
Actual, Amount	$ 372,679	$ 345,065
Actual, Ratio	0.0876	0.0919
Requirement for Capital Adequacy Purposes, Amount	$ 170,245	$ 169,940
Requirement for Capital Adequacy Purposes, Ratio	0.040	0.040
To be Well Capitalized Under Prompt Corrective Action Provisions, Amount	$ 212,807	$ 212,425
To be Well Capitalized Under Prompt Corrective Action Provisions, Ratio	0.050	0.050