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Amount of additional first mortgage bonds and general mortgage bonds that could be issued on the basis of retired bonds and 70% of property additions as of the balance sheet date.

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Amount of Securitiztion Bonds Authorized To Issue

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Debt Instrument, Amount Of Debt Cancelled

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Debt Instrument, Cash Tender Offer, Purchase Amount

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Debt Instrument, Debt Maturity Selection, Number Of Business Days For Advance Notice

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Debt Instrument, Extension Term

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Debt Instrument, Redemption Price, Principal Amount Repurchased

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Percentage Of Property Additions

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Securitiztion Bonds Authorized To Issue, Interest Rate, Percent

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Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

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The price per share of the conversion feature embedded in the debt instrument.

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Ratio applied to the conversion of debt instrument into equity with equity shares divided by debt principal amount.

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The number of equity instruments that the holder of the debt instrument would receive if the debt was converted to equity.

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Minimum percentage of common stock price to conversion price of convertible debt instruments to determine eligibility of conversion.

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Face (par) amount of debt instrument at time of issuance.

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Contractual interest rate for funds borrowed, under the debt agreement.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Short-term Borrowings and Long-term Debt - Narrative (Details) $ / shares in Units, $ in Millions						1 Months Ended						9 Months Ended
	Jul. 31, 2025 USD ($)	Jul. 28, 2025 $ / shares	Jul. 01, 2025 USD ($)	Jan. 31, 2025 USD ($)	Jan. 29, 2025	Aug. 31, 2025 USD ($)	Jul. 24, 2025 USD ($)	Jun. 30, 2025 USD ($)	May 31, 2025 USD ($)	Mar. 31, 2025 USD ($)	Feb. 28, 2025 USD ($)	Sep. 30, 2025 USD ($) shares	Jun. 20, 2025 USD ($)	Apr. 30, 2025 USD ($)
Debt Instrument [Line Items]
Regulatory asset, authorized issuance costs													$ 401.5
Credit agreement term (in years)					1 year
CERC
Debt Instrument [Line Items]
Gain from early extinguishment of debt												$ 9.0
Parent Company
Debt Instrument [Line Items]
Gain from early extinguishment of debt												$ 36.0
SIGECO
Debt Instrument [Line Items]
Percentage of property additions (as a percent)												70.00%
Outstanding debt balance												$ 1,300.0
Additional debt issuable												944.0
Houston Electric
Debt Instrument [Line Items]
Regulatory asset, authorized issuance costs												401.5
Additional first mortgage bonds and general mortgage bonds that could be issued												$ 4,300.0
Houston Electric \| Minimum
Debt Instrument [Line Items]
Securitiztion bonds interest rate (in percent)												4.255%
Houston Electric \| Maximum
Debt Instrument [Line Items]
Securitiztion bonds interest rate (in percent)												4.826%
Senior Notes
Debt Instrument [Line Items]
Principal amount repurchased									$ 1,000.0
Senior Notes \| Parent Company
Debt Instrument [Line Items]
Amount of cancelled debt									634.0
Senior Notes \| CERC
Debt Instrument [Line Items]
Amount of cancelled debt									$ 415.0
General Mortgage Bonds, 2.35% to 6.95%, Due 2026 to 2053 \| Houston Electric
Debt Instrument [Line Items]
Secured debt												$ 9,600.0
Bonds Pollution Control Due Range 1 \| Houston Electric
Debt Instrument [Line Items]
Secured debt												$ 68.0
Percentage of property additions (as a percent)												70.00%
5.69% First Mortgage Bonds, Series 2025A \| First Mortgage Bonds \| SIGECO
Debt Instrument [Line Items]
Aggregate principal				$ 165.0
Annual interest rate (as a percent)				5.69%
Proceeds from issuance of long-term debt and capital securities, net				$ 164.0
General Mortgage Bonds 5.15% Due 2034 \| General Mortgage Bonds \| Houston Electric
Debt Instrument [Line Items]
Aggregate principal											$ 500.0
Annual interest rate (as a percent)											4.80%
Proceeds from issuance of long-term debt and capital securities, net											$ 495.0
5.09%, Series 2025B, Tranche A Due 2031 \| First Mortgage Bonds \| SIGECO \| Long-term Debt
Debt Instrument [Line Items]
Aggregate principal			$ 100.0
Annual interest rate (as a percent)			5.09%
5.52%, Series 2025B, Tranche A Due 2035 \| First Mortgage Bonds \| SIGECO \| Long-term Debt
Debt Instrument [Line Items]
Aggregate principal			$ 105.0
Annual interest rate (as a percent)			5.52%
5.77%, Series 2025C, Tranche A Due 2040 \| First Mortgage Bonds \| SIGECO \| Long-term Debt
Debt Instrument [Line Items]
Aggregate principal			$ 45.0
Annual interest rate (as a percent)			5.77%
Number of business days			5 days
6.18%, Series 2025C, Tranche B Due 2055 \| First Mortgage Bonds \| SIGECO \| Long-term Debt
Debt Instrument [Line Items]
Aggregate principal			$ 100.0
Annual interest rate (as a percent)			6.18%
Series 2025B Bonds \| SIGECO \| Long-term Debt
Debt Instrument [Line Items]
Aggregate principal			$ 205.0
4.95%, General Mortgage Bonds, Series AQ, due 2035 \| General Mortgage Bonds \| Houston Electric \| Long-term Debt
Debt Instrument [Line Items]
Aggregate principal						$ 600.0
Annual interest rate (as a percent)						4.95%
Proceeds from issuance of long-term debt and capital securities, net						$ 592.0
Convertible Senior Notes, Due 2028
Debt Instrument [Line Items]
Debt instrument, convertible, conversion ratio		21.4477
Conversion price percentage		25.00%
Convertible Senior Notes, Due 2028 \| Maximum
Debt Instrument [Line Items]
Debt instrument, convertible, conversion ratio												26.8096
Debt instrument, convertible, number of equity instruments (in shares) \| shares												26,809,600
Convertible Senior Notes, Due 2028 \| Convertible Debt
Debt Instrument [Line Items]
Aggregate principal	$ 1,000.0
Annual interest rate (as a percent)	3.00%
Proceeds from issuance of long-term debt and capital securities, net	$ 987.0
Debt instrument, convertible, conversion price (in dollar per shares) \| $ / shares		$ 46.63
Debt instrument, redemption price, percentage		100.00%
Medium Term Notes, Series F, Due 2028 \| CERC
Debt Instrument [Line Items]
Annual interest rate (as a percent)										6.36%
Principal amount repurchased										$ 10.0
Debt instrument, redemption price, percentage of principal amount redeemed										104.80%
Senior Notes Due 2026 to 2031 \| Senior Notes
Debt Instrument [Line Items]
Cash tender offers														$ 600.0
Senior Notes Due 2026 to 2031 \| Senior Notes \| Minimum
Debt Instrument [Line Items]
Annual interest rate (as a percent)														2.65%
Senior Notes Due 2026 to 2031 \| Senior Notes \| Maximum
Debt Instrument [Line Items]
Annual interest rate (as a percent)														5.40%
Senior Notes Due 2028 to 2047 \| Senior Notes \| Minimum
Debt Instrument [Line Items]
Annual interest rate (as a percent)														4.10%
Senior Notes Due 2028 to 2047 \| Senior Notes \| Maximum
Debt Instrument [Line Items]
Annual interest rate (as a percent)														5.40%
Senior Notes Due 2028 to 2047 \| Senior Notes \| CERC
Debt Instrument [Line Items]
Cash tender offers														$ 400.0
Medium Term Notes, Series E, Due 2025 \| CERC
Debt Instrument [Line Items]
Annual interest rate (as a percent)								6.53%
Principal amount repurchased								$ 10.0
Debt instrument, redemption price, percentage of principal amount redeemed								100.00%
First Mortgage Bonds 3.45% Due 2025 \| First Mortgage Bonds \| SIGECO \| Long-term Debt
Debt Instrument [Line Items]
Aggregate principal							$ 41.0
Annual interest rate (as a percent)							3.45%
Debt instrument, redemption price, percentage							100.00%