| Cover | Mar. 09, 2021 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Document Period End Date | Mar. 9, 2021 |
| Entity Registrant Name | 9 Meters Biopharma, Inc. |
| Entity Incorporation, State or Country Code | DE |
| Entity File Number | 001-37797 |
| Entity Tax Identification Number | 27-3948465 |
| Entity Address, Address Line One | 8480 Honeycutt Road |
| Entity Address, Address Line Two | Suite 120 |
| Entity Address, City or Town | Raleigh |
| Entity Address, State or Province | NC |
| Entity Address, Postal Zip Code | 27615 |
| City Area Code | 919 |
| Local Phone Number | 275-1933 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common Stock $0.0001 Par Value |
| Trading Symbol | NMTR |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | true |
| Entity Ex Transition Period | true |
| Entity Central Index Key | 0001551986 |
| Amendment Flag | false |
