Short-Term Debt and Credit Facility Short-Term Debt and Credit Facility (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Line of Credit Facility [Line Items]
Advances to parent	$ 304.8	$ 319.5
Outstanding Intercompany Borrowings	0.0
OG&E [Member]
Line of Credit Facility [Line Items]
Intercompany Borrowings, Maximum Borrowing Capacity	$ 350.0
Intercompany Borrowing Agreement, Expiration Date	Mar. 08, 2023
Letters of Credit Outstanding, Amount	$ 0.3
Short-term Debt, Weighted Average Interest Rate, at Point in Time	1.00%
Commercial Paper	$ 0.0
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
Ratio of Consolidated Debt to Consolidated Capitalization	65.00%
Uninsured Judgements [Member] | OG&E [Member]
Line of Credit Facility [Line Items]
Acceleration of Indebtedness of Credit Facility	$ 100.0
Uninsured Judgements [Member] | OGE Energy [Member]
Line of Credit Facility [Line Items]
Acceleration of Indebtedness of Credit Facility	$ 100.0