| Document and Entity Information Document | Jan. 28, 2021 | Dec. 02, 2020 |
| Entity Information [Line Items] | ||
| Entity Central Index Key | 0001021635 | |
| Document Type | 8-K | |
| City Area Code | 405 | |
| Local Phone Number | 553-3000 | |
| Entity Emerging Growth Company | false | |
| Title of 12(b) Security | Common Stock | |
| Written Communications | false | |
| Document Period End Date | Jan. 28, 2021 | |
| Entity Registrant Name | OGE ENERGY CORP. | |
| Entity Incorporation, State or Country Code | OK | |
| Entity File Number | 1-12579 | |
| Entity Tax Identification Number | 73-1481638 | |
| Entity Address, Address Line One | 321 North Harvey | |
| Entity Address, Address Line Two | P.O. Box 321 | |
| Entity Address, City or Town | Oklahoma City | |
| Entity Address, State or Province | OK | |
| Entity Address, Postal Zip Code | 73101-0321 | |
| Soliciting Material | false | |
| Pre-commencement Tender Offer | false | |
| Pre-commencement Issuer Tender Offer | false | |
| Trading Symbol | OGE | |
| Security Exchange Name | NYSE | |
| Amendment Flag | false |
