Short-Term Debt and Credit Facilities (Details) - USD ($) $ in Millions		3 Months Ended	9 Months Ended
		Mar. 31, 2021	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Line of Credit Facility [Line Items]
Short-term debt			$ 383.2		$ 95.0
Line of Credit Facility [Abstract]
Aggregate Commitment			900.0
Long-term Line of Credit	[1]		$ 283.6
Weighted Average Interest Rate			0.18%
Debt Instrument, Face Amount			$ 1,000.0
Proceeds from Contributed Capital		$ 530.0
Debt, Weighted Average Interest Rate			0.832%
OGE Energy [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Current Borrowing Capacity	[2]		$ 450.0
Line of Credit Facility [Abstract]
Long-term Line of Credit	[1],[2]		$ 283.2
Weighted Average Interest Rate	[2],[3]		0.18%
Maturity	[2],[4]		Mar. 08, 2024
OGE Energy [Member] | Not Extended
Line of Credit Facility [Line Items]
Line of Credit Facility, Current Borrowing Capacity			$ 50.0
Line of Credit Facility [Abstract]
Maturity			Mar. 08, 2023
OG&E [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Current Borrowing Capacity	[5],[6]		$ 450.0
Line of Credit Facility [Abstract]
Letters of Credit Outstanding, Amount	[1],[5],[6]		$ 0.4
Weighted Average Interest Rate	[3],[5],[6]		1.15%
Maturity	[4],[5],[6]		Mar. 08, 2024
Short Term Borrowing Capacity That Has Regulatory Approval			$ 800.0
Period For Which Regulatory Approval Has Been Given to Acquire Short Term Debt			2 years
Intercompany borrowing agreement, maximum borrowing capacity			$ 350.0
Outstanding intercompany borrowings			0.0
Proceeds from Loans			470.0
Advances from parent			42.2		0.0
Advances to parent			0.0		$ 272.0
Proceeds from Contributed Capital		$ 530.0	$ 530.0	$ 0.0

[1] Includes direct borrowings under the revolving credit agreements, commercial paper borrowings and letters of credit at September 30, 2021.

[2] This bank facility is available to back up OGE Energy's commercial paper borrowings and to provide revolving credit borrowings. This bank facility can also be used as a letter of credit facility.  

[3] Represents the weighted-average interest rate for the outstanding borrowings under the revolving credit agreements, commercial paper borrowings and letters of credit.

[4] In March 2017, the Registrants entered into unsecured five-year revolving credit agreements totaling $900.0 million ($450.0 million for OGE Energy and $450.0 million for OG&E). Each of the revolving credit facilities contained an option, which could be exercised up to two times, to extend the term of the respective facility for an additional year. In March 2018, the Registrants each utilized one of those extensions to extend the maturity of their respective credit facility from March 8, 2022 to March 8, 2023. In January 2021, the Registrants each utilized the second of those extensions to extend the maturity of their respective credit facility from March 8, 2023 to March 8, 2024. Commitments of a single existing lender with respect to $50.0 million of OGE Energy's credit facility, however, were not extended and, unless the non-extending lender is replaced in accordance with the terms of the credit facility, such commitments will expire March 8, 2023. The non-extending lender is not party to the OG&E facility.

[5] OG&E has an intercompany borrowing agreement with OGE Energy whereby OG&E has access to up to $350.0 million of OGE Energy's revolving credit amount. This agreement has a termination date of March 8, 2024. At September 30, 2021, there were no intercompany borrowings under this agreement. 

[6] This bank facility is available to back up OG&E's commercial paper borrowings and to provide revolving credit borrowings. This bank facility can also be used as a letter of credit facility.