Fair Value Measurements - Summary of Financial Instrument Measured at Fair Value On A Recurring Basis and Carrying Amount and Fair Value (Details) - USD ($) $ in Millions	Jun. 30, 2025	Dec. 31, 2024
OGE Energy Senior Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total long-term debt	$ 347.2	$ 346.9
Long-Term Debt, Fair Value	362.3	355.7
OGE Energy Term Loan [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total long-term debt	59.8	59.7
Long-Term Debt, Fair Value	60.0	60.0
OG&E Senior Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total long-term debt	4,845.5	4,499.6
Long-Term Debt, Fair Value	4,596.9	4,174.9
OG&E Industrial Authority Bonds [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total long-term debt	103.0	135.4
Long-Term Debt, Fair Value	103.0	135.4
OG&E Tinker Debt [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total long-term debt	11.7	11.7
Long-Term Debt, Fair Value	$ 9.0	$ 9.0