| Document And Entity Information | Mar. 23, 2023 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Mar. 23, 2023 |
| Entity Registrant Name | PHX MINERALS INC. |
| Entity Central Index Key | 0000315131 |
| Entity Emerging Growth Company | false |
| Securities Act File Number | 001-31759 |
| Entity Incorporation, State or Country Code | DE |
| Entity Tax Identification Number | 73-1055775 |
| Entity Address, Address Line One | 1320 South University Drive |
| Entity Address, Address Line Two | Suite 720 |
| Entity Address, City or Town | Fort Worth |
| Entity Address, State or Province | TX |
| Entity Address, Postal Zip Code | 76107 |
| City Area Code | (405) |
| Local Phone Number | 948-1560 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common Stock, $0.01666 par value |
| Trading Symbol | PHX |
| Security Exchange Name | NYSE |
