| Document And Entity Information | Nov. 03, 2021 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Document Period End Date | Nov. 3, 2021 |
| Entity File Number | 001-39182 |
| Entity Registrant Name | FFBW, INC. /MD/ |
| Entity Incorporation, State or Country Code | MD |
| Entity Tax Identification Number | 37-1962248 |
| Entity Address, Address Line One | 1360 South Moorland Road |
| Entity Address, City or Town | Brookfield |
| Entity Address, State or Province | WI |
| Entity Address, Postal Zip Code | 53005 |
| City Area Code | 262 |
| Local Phone Number | 542-4448 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common Stock, par value $0.01 per share |
| Trading Symbol | FFBW |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | true |
| Entity Ex Transition Period | false |
| Entity Central Index Key | 0001787384 |
| Amendment Flag | false |
