Rate Matters and Regulation - Additional Information (Details) $ in Millions					1 Months Ended	12 Months Ended
	Jun. 12, 2024 USD ($)	Mar. 07, 2024 USD ($)	Jan. 19, 2024 Megawattsday	Dec. 29, 2023 USD ($)	Jan. 31, 2023	Dec. 31, 2028 Megawattsday	Dec. 31, 2027 Megawattsday	Dec. 31, 2026 Megawattsday	Sep. 30, 2024 USD ($)
Estimated Refund to SPP									$ 13.0
Requested Recovery of Capital Investment				$ 1,300.0
Recovery of regulatory asset period					10 years
Pre-tax weighted average cost of capital percentage					6.49%
Arkansas Public Service Commission [Member]
Public Utilities, Approved Rate Increase (Decrease), Amount		$ 3.5
Arkansas 2024 Generation Construction Notice Filing
Energy generation capacity \| Megawattsday			96
Integrated Resource Plans [Member] \| Forecast [Member]
Energy generation capacity \| Megawattsday						1,096	431	556
OKLAHOMA [Member]
Public Utilities, Requested Rate Increase (Decrease), Amount	$ 126.7			$ 332.5
Public Utilities, Requested Return on Equity, Percentage				10.50%
Common Equity Percentage which ROE is based				53.50%
Impact to Company [Member]
Estimated Refund to SPP									5.0
Customer Impact [Member]
Estimated Refund to SPP									$ 8.0