| Document and Entity Information | Mar. 14, 2023 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Document Period End Date | Mar. 14, 2023 |
| Entity Registrant Name | SYSTEM ENERGY RESOURCES, INC |
| Entity Incorporation, State or Country Code | AR |
| Entity File Number | 1-09067 |
| Entity Tax Identification Number | 72-0752777 |
| Entity Address, Address Line One | 1340 Echelon Parkway |
| Entity Address, City or Town | Jackson |
| Entity Address, State or Province | MS |
| Entity Address, Postal Zip Code | 39213 |
| City Area Code | 601 |
| Local Phone Number | 368-5000 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Entity Emerging Growth Company | false |
| Amendment Flag | false |
| Entity Central Index Key | 0000202584 |
