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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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Debt Instrument, Amount Of Debt Cancelled

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Debt Instrument, Cash Tender Offer, Purchase Amount

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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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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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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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Percentage of principal amount of debt redeemed.

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Difference between the fair value of payments made and the carrying amount of debt which is extinguished prior to maturity.

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Carrying value as of the balance sheet date, including the current and noncurrent portions, of collateralized debt obligations (with maturities initially due after one year or beyond the operating cycle, if longer). Such obligations include mortgage loans, chattel loans, and any other borrowings secured by assets of the borrower.

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Short-term Borrowings and Long-term Debt - Narrative (Details) - USD ($) $ in Millions			1 Months Ended				3 Months Ended
	Jan. 31, 2025	Jan. 29, 2025	Jun. 30, 2025	May 31, 2025	Mar. 31, 2025	Feb. 28, 2025	Jun. 30, 2025	Apr. 30, 2025
Debt Instrument [Line Items]
Credit agreement term (in years)		1 year
CERC
Debt Instrument [Line Items]
Gain from early extinguishment of debt							$ 9
Parent Company
Debt Instrument [Line Items]
Gain from early extinguishment of debt							$ 36
SIGECO
Debt Instrument [Line Items]
Percentage of property additions (as a percent)			70.00%				70.00%
Outstanding debt balance			$ 1,100				$ 1,100
Additional debt issuable			1,100				1,100
Houston Electric
Debt Instrument [Line Items]
Additional first mortgage bonds and general mortgage bonds that could be issued			4,500				4,500
Senior Notes
Debt Instrument [Line Items]
Principal amount repurchased				$ 1,000
Senior Notes \| Parent Company
Debt Instrument [Line Items]
Amount of cancelled debt				634
Senior Notes \| CERC
Debt Instrument [Line Items]
Amount of cancelled debt				$ 415
General Mortgage Bonds, 2.35% to 6.95%, Due 2026 to 2053 \| Houston Electric
Debt Instrument [Line Items]
Secured debt			9,000				9,000
Bonds Pollution Control Due Range 1 \| Houston Electric
Debt Instrument [Line Items]
Secured debt			$ 68				$ 68
Percentage of property additions (as a percent)			70.00%				70.00%
5.69% First Mortgage Bonds, Series 2025A \| First Mortgage Bonds \| SIGECO
Debt Instrument [Line Items]
Aggregate principal	$ 165
Annual interest rate (as a percent)	5.69%
Proceeds from issuance of long-term debt and capital securities, net	$ 164
General Mortgage Bonds 5.15% Due 2034 \| General Mortgage Bonds \| Houston Electric
Debt Instrument [Line Items]
Aggregate principal						$ 500
Annual interest rate (as a percent)						4.80%
Proceeds from issuance of long-term debt and capital securities, net						$ 495
Medium Term Notes, Series F, Due 2028 \| CERC
Debt Instrument [Line Items]
Annual interest rate (as a percent)					6.36%
Principal amount repurchased					$ 10
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
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
Medium Term Notes, Series E, Due 2025 \| CERC
Debt Instrument [Line Items]
Annual interest rate (as a percent)			6.53%				6.53%
Principal amount repurchased			$ 10
Debt instrument, redemption price, percentage of principal amount redeemed			100.00%