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Short-term Borrowings and Long-term Debt - Schedule of Debt Instruments Were Repaid at Maturity (Details) - Long-term Debt - USD ($) $ in Millions			1 Months Ended
	May 13, 2024	Mar. 01, 2024	Sep. 30, 2024	Dec. 31, 2024
Debt Instrument [Line Items]
Aggregate Principal				$ 872
First Mortgage Bonds \| First Mortgage Bonds \| SIGECO
Debt Instrument [Line Items]
Aggregate Principal		$ 22		$ 22
Interest Rate				3.50%
Debt instrument, redemption price (as a percent)		100.00%
Senior Notes, 0.65%, Due 2024 \| Senior Notes
Debt Instrument [Line Items]
Aggregate Principal	$ 350			$ 350
Interest Rate				65.00%
Debt instrument, redemption price (as a percent)	100.00%
Senior Notes 2.50%, Due 2024 \| Senior Notes
Debt Instrument [Line Items]
Aggregate Principal			$ 500	$ 500
Interest Rate			2.50%	2.50%
Debt instrument, redemption price (as a percent)			100.00%