| Document and Entity Information Document | Aug. 18, 2021 |
| Entity Information [Line Items] | |
| Document Type | 8-K |
| Document Period End Date | Mar. 10, 2022 |
| Entity Registrant Name | LUMOS PHARMA, INC. |
| Entity Central Index Key | 0001126234 |
| Amendment Flag | false |
| Entity Incorporation, State or Country Code | DE |
| Entity File Number | 001-35342 |
| Entity Tax Identification Number | 42-1491350 |
| City Area Code | 512 |
| Local Phone Number | 215-2630 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common Stock |
| Trading Symbol | LUMO |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | false |
| Entity Address, Address Line One | 4200 Marathon Blvd., Suite 200 |
| Entity Address, Postal Zip Code | 78756 |
| Entity Address, City or Town | Austin |
| Entity Address, State or Province | TX |
