Summary of Significant Accounting Policies - Summary of Changes to Asset Retirement Obligation (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2023	Dec. 31, 2022
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Balance at January 1		$ 78.3	$ 80.2
Accretion expense		0.7	0.6
Liabilities settled	[1]	0.0	(2.5)
Revisions in estimated cash flows	[2]	2.3	0.0
Balance at December 31		$ 81.3	$ 78.3

[1] (A) Asset retirement obligations were settled for asbestos removal at OG&E's generating facilities.

[2] (B) Assumptions changed related to the estimated timing and estimated cost of the removal of asbestos at OG&E's generating facilities.