| Document and Entity Information | Apr. 26, 2021 |
| Document and Entity Information [Abstract] | |
| Entity Central Index Key | 0000740806 |
| Amendment Flag | false |
| Document Type | 8-K |
| Document Period End Date | Apr. 26, 2021 |
| Entity Registrant Name | F&M BANK CORP |
| Entity Incorporation, State or Country Code | VA |
| Entity File Number | 000-13273 |
| Entity Tax Identification Number | 54-1280811 |
| Entity Address, Address Line One | P.O. Box 1111 |
| Entity Address, City or Town | Timberville |
| Entity Address, State or Province | VA |
| Entity Address, Postal Zip Code | 22853 |
| City Area Code | 540 |
| Local Phone Number | 896-8941 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Entity Emerging Growth Company | false |
