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Short-term Borrowings and Long-term Debt - Narrative (Details) $ / shares in Units, $ in Millions		1 Months Ended					3 Months Ended	9 Months Ended
	Aug. 01, 2023 $ / shares	Sep. 30, 2024 USD ($)	Aug. 31, 2024 USD ($) lawsuit	Jun. 30, 2024 USD ($)	May 31, 2024 USD ($)	Feb. 29, 2024 USD ($)	Mar. 31, 2024 USD ($)	Sep. 30, 2024 USD ($) shares period	Aug. 29, 2024 USD ($)	Jun. 28, 2024 USD ($)	Dec. 31, 2023 USD ($)
Debt Instrument [Line Items]
Debt instrument, convertible, conversion ratio	27.1278
Conversion price (as a percent)	25.00%
Maximum
Debt Instrument [Line Items]
Debt instrument, convertible, conversion ratio								33.9097
Debt instrument, convertible, number of equity instruments (in shares) | shares								33,909,700
First Mortgage Bonds | Tranche A Due 2034
Debt Instrument [Line Items]
Debt instrument, face amount									$ 100
Annual interest rate (as a percent)									5.18%
First Mortgage Bonds | Tranche B Due 2036
Debt Instrument [Line Items]
Debt instrument, face amount									$ 60
Annual interest rate (as a percent)									5.28%
First Mortgage Bonds | Tranche A Due 2055
Debt Instrument [Line Items]
Debt instrument, face amount									$ 165
Annual interest rate (as a percent)									5.69%
Junior Notes | Maximum
Debt Instrument [Line Items]
Deferral period | period								20
Convertible Debt
Debt Instrument [Line Items]
Debt instrument, convertible, conversion price (in dollar per shares) | $ / shares	$ 36.86
Debt instrument, redemption price (as a percent)	100.00%
Senior Notes Due 2029
Debt Instrument [Line Items]
Debt instrument, face amount					$ 700
Annual interest rate (as a percent)					5.40%
Proceeds from issuance of long-term debt and capital securities, net					$ 693
Senior Notes Due 2024
Debt Instrument [Line Items]
Annual interest rate (as a percent)		2.50%						2.50%
Debt instrument, redemption price, principal amount redeemed		$ 500			$ 350
Debt instrument, redemption price, percentage of principal amount redeemed		100.00%			100.00%
Junior Subordinated Notes Due 2055 | Junior Notes
Debt Instrument [Line Items]
Debt instrument, face amount			$ 400
Weighted Average Interest Rate			7.00%
Series B Junior Subordinated Notes Due 2055 | Junior Notes
Debt Instrument [Line Items]
Debt instrument, face amount			$ 400
Weighted Average Interest Rate			6.85%
Series A Junior Subordinated Notes Due 2030 | Junior Notes
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)			7.00%
Debt instrument, interest rate, period			5 years
Number of days before interest rate period | lawsuit			2
Series A Junior Subordinated Notes Due 2035 | Junior Notes
Debt Instrument [Line Items]
Debt instrument, interest rate, period			5 years
Number of days before interest rate period | lawsuit			2
Junior Subordinated Notes Due 2024
Debt Instrument [Line Items]
Size of Facility			$ 790
First Mortgage Bonds 3.50% Due 2024 | SIGECO
Debt Instrument [Line Items]
Annual interest rate (as a percent)							3.50%
Debt instrument, redemption price, principal amount redeemed							$ 22
Debt instrument, redemption price, percentage of principal amount redeemed							100.00%
Series A, 3 Point 254 Percent, Junior Subordinated Notes Due 2030 | Junior Notes
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)			3.254%
Series B, 6 Point 850 Percent, Junior Subordinated Notes Due 2030 | Junior Notes
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)			6.85%
Series B, 2 Point 946 Percent, Junior Subordinated Notes Due 2030 | Junior Notes
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)			2.946%
CERC | Senior Notes Due 2034
Debt Instrument [Line Items]
Debt instrument, face amount				$ 400
Annual interest rate (as a percent)				5.40%
Proceeds from issuance of long-term debt and capital securities, net				$ 396
Houston Electric | General Mortgage Bonds
Debt Instrument [Line Items]
Secured debt		$ 8,000						$ 8,000
General mortgage bonds used as collateral		$ 68						$ 68
Percentage of property additions		70.00%						70.00%
Additional first mortgage bonds and general mortgage bonds that could be issued		$ 5,100						$ 5,100
Percentage of property additions (as a percent)		70.00%						70.00%
Houston Electric | General Mortgage Bonds 5.15% Due 2034 | General Mortgage Bonds
Debt Instrument [Line Items]
Debt instrument, face amount						$ 400
Annual interest rate (as a percent)						5.15%
Proceeds from issuance of long-term debt and capital securities, net						$ 395
Houston Electric | Delayed Draw Term Loan (DDTL)
Debt Instrument [Line Items]
Debt instrument, face amount				300
Additional borrowing capacity				$ 200
Debt instrument, interest rate, stated percentage, annual adjustment (as a percent)				0.10%
Basis spread on variable rate (as a percent)				1.00%
Size of Facility		$ 200						$ 200		$ 100
SIGECO | First Mortgage Bonds
Debt Instrument [Line Items]
Secured debt		985						985
Additional first mortgage bonds and general mortgage bonds that could be issued		$ 814						$ 814
Percentage of property additions (as a percent)		70.00%						70.00%
SIGECO | Series 2024A Bond
Debt Instrument [Line Items]
Debt instrument, face amount									$ 160
Third Party AMAs
Debt Instrument [Line Items]
Inventory financings		$ 3						$ 3			$ 4
Third Party AMAs | CERC
Debt Instrument [Line Items]
Inventory financings		$ 3						$ 3			$ 4

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