Short-term Borrowings and Long-term Debt - Schedule of Revolving Credit Facilities (Details) $ in Millions	12 Months Ended
Dec. 31, 2022 USD ($) day	Dec. 31, 2021 USD ($)
Debt Instrument [Line Items]
Size of credit facility	$ 4,000	$ 4,000
Number of days until commercial paper maturity \| day	60
Houston Electric
Debt Instrument [Line Items]
Size of credit facility	$ 300	300
CERC Corp
Debt Instrument [Line Items]
Size of credit facility	$ 1,050	900
Number of days until commercial paper maturity \| day	30
SIGECO
Debt Instrument [Line Items]
Size of credit facility	$ 250	0
Line of Credit \| Houston Electric
Debt Instrument [Line Items]
Percentage on limitation of debt to total capitalization under covenant (in hundredths)	67.50%
Ratio of indebtedness to net capital	0.544
Line of Credit \| CERC Corp
Debt Instrument [Line Items]
Percentage on limitation of debt to total capitalization under covenant (in hundredths)	65.00%
Ratio of indebtedness to net capital	0.499
Line of Credit \| SIGECO
Debt Instrument [Line Items]
Percentage on limitation of debt to total capitalization under covenant (in hundredths)	65.00%
Ratio of indebtedness to net capital	0.452
Line of Credit \| London Interbank Offered Rate (LIBOR) \| Houston Electric
Debt Instrument [Line Items]
Basis spread (as a percent)	1.25%
Line of Credit \| London Interbank Offered Rate (LIBOR) \| CERC Corp
Debt Instrument [Line Items]
Basis spread (as a percent)	1.125%
Line of Credit \| London Interbank Offered Rate (LIBOR) \| SIGECO
Debt Instrument [Line Items]
Basis spread (as a percent)	1.125%
Revolving Credit Facility
Debt Instrument [Line Items]
Loans	$ 0	0
Revolving Credit Facility \| Houston Electric
Debt Instrument [Line Items]
Loans	0	0
Revolving Credit Facility \| CERC Corp
Debt Instrument [Line Items]
Loans	0	0
Revolving Credit Facility \| SIGECO
Debt Instrument [Line Items]
Loans	0	0
Letter of Credit
Debt Instrument [Line Items]
Loans	11	11
Letter of Credit \| Houston Electric
Debt Instrument [Line Items]
Loans	0	0
Letter of Credit \| CERC Corp
Debt Instrument [Line Items]
Loans	0	0
Letter of Credit \| SIGECO
Debt Instrument [Line Items]
Loans	0	0
Commercial paper
Debt Instrument [Line Items]
Loans	2,575	2,649
Commercial paper \| Houston Electric
Debt Instrument [Line Items]
Loans	$ 0	$ 0
Weighted average interest rate (as a percent)	0.00%	0.00%
Commercial paper \| CERC Corp
Debt Instrument [Line Items]
Loans	$ 805	$ 899
Weighted average interest rate (as a percent)	4.67%	0.26%
Commercial paper \| SIGECO
Debt Instrument [Line Items]
Loans	$ 0	$ 0
Weighted average interest rate (as a percent)	0.00%	0.00%
Parent Company
Debt Instrument [Line Items]
Size of credit facility	$ 2,400	$ 2,400
Parent Company \| Line of Credit
Debt Instrument [Line Items]
Percentage on limitation of debt to total capitalization under covenant (in hundredths)	65.00%
Ratio of indebtedness to net capital	0.618
Percentage on limitation of debt to total capitalization under covenant amended (in hundredths)	70.00%
Expected restoration costs	$ 100
Consecutive period for system restoration costs to exceed $100 million (in months)	12
Parent Company \| Line of Credit \| London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Basis spread (as a percent)	1.50%
Parent Company \| Revolving Credit Facility
Debt Instrument [Line Items]
Loans	$ 0	0
Parent Company \| Letter of Credit
Debt Instrument [Line Items]
Loans	11	11
Parent Company \| Commercial paper
Debt Instrument [Line Items]
Loans	$ 1,770	$ 1,400
Weighted average interest rate (as a percent)	4.71%	0.34%
VUH \| Revolving Credit Facility
Debt Instrument [Line Items]
Size of credit facility	$ 0	$ 400
Loans	0	0
VUH \| Letter of Credit
Debt Instrument [Line Items]
Loans	0	0
VUH \| Commercial paper
Debt Instrument [Line Items]
Loans	$ 0	$ 350
Weighted average interest rate (as a percent)	0.00%	0.21%

Consecutive Period for System Restoration Costs to Exceed $100 million (in months)

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Number of days until commercial paper maturity.

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- Definition

Percentage on limitation of debt to total capitalization under covenant.

+ References

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Temporary increased percentage on limitation of debt to total capitalization under covenant (in hundredths)

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The minimum amount of estimated restoration cost in a calendar year in order for a temporary increase in debt to EBITDA covenant

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- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

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Weighted average interest rate of debt outstanding.

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- Definition

The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
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-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
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-Subparagraph (SX 210.9-03(16))
-URI https://asc.fasb.org/extlink&oid=126897435&loc=d3e534808-122878

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-Name Accounting Standards Codification
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- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

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- Definition

Indebtedness divided by net capital.

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