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Short-term Borrowings and Long-term Debt - Narrative (Details) $ / shares in Units, $ in Millions		1 Months Ended	3 Months Ended
	Aug. 01, 2023 $ / shares	Feb. 29, 2024 USD ($)	Mar. 31, 2024 USD ($) shares	Dec. 31, 2023 USD ($)
Debt Instrument [Line Items]
Debt instrument, convertible, conversion ratio	27.1278
Conversion price percentage	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
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%
First Mortgage Bonds 3.50% Due 2024 | SIGECO
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage			3.50%
Debt instrument, redemption price, principal amount redeemed			$ 22
Debt instrument, redemption price, percentage of principal amount redeemed			100.00%
Houston Electric | General Mortgage Bonds
Debt Instrument [Line Items]
Secured debt			$ 8,000
General mortgage bonds used as collateral			$ 68
Percentage of property additions			70.00%
Additional first mortgage bonds and general mortgage bonds that could be issued			$ 4,600
Percentage of property additions (as a percent)			70.00%
Houston Electric | General Mortgage Bonds 5.15% Due 2034 | General Mortgage Bonds
Debt Instrument [Line Items]
Debt instrument, face amount		$ 400
Debt instrument, interest rate, stated percentage		5.15%
Proceeds from issuance of long-term debt and capital securities, net		$ 395
SIGECO | First Mortgage Bonds
Debt Instrument [Line Items]
Secured debt			$ 825
Additional first mortgage bonds and general mortgage bonds that could be issued			$ 966
Percentage of property additions (as a percent)			70.00%
Third Party AMAs
Debt Instrument [Line Items]
Inventory financings			$ 0	$ 4
Third Party AMAs | CERC
Debt Instrument [Line Items]
Inventory financings			$ 0	$ 4

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