Short-term Borrowings and Long-term Debt - Schedule of Revolving Credit Facilities (Details) $ in Millions	3 Months Ended
Mar. 31, 2023 USD ($)
Debt Instrument [Line Items]
Aggregate principal amount	$ 4,000
Houston Electric
Debt Instrument [Line Items]
Aggregate principal amount	300
Restoration costs	100
CERC
Debt Instrument [Line Items]
Aggregate principal amount	$ 1,050
Line of Credit \| Maximum
Debt Instrument [Line Items]
Percentage on limitation of debt to total capitalization under covenant amended (in hundredths) (as a percent)	70.00%
Line of Credit \| Houston Electric
Debt Instrument [Line Items]
Ratio of indebtedness to net capital (as a percent)	0.675
Percentage on limitation of debt to total capitalization under covenant (as a percent)	52.40%
Consecutive period for system restoration costs to exceed $100 million (in months)	12 months
Line of Credit \| Houston Electric \| Maximum
Debt Instrument [Line Items]
Percentage on limitation of debt to total capitalization under covenant amended (in hundredths) (as a percent)	70.00%
Line of Credit \| CERC
Debt Instrument [Line Items]
Ratio of indebtedness to net capital (as a percent)	0.650
Percentage on limitation of debt to total capitalization under covenant (as a percent)	45.20%
Line of Credit \| SOFR Plus \| Houston Electric
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)	1.25%
Line of Credit \| SOFR Plus \| CERC
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)	1.125%
Parent Company
Debt Instrument [Line Items]
Aggregate principal amount	$ 2,400
Parent Company \| Line of Credit
Debt Instrument [Line Items]
Ratio of indebtedness to net capital (as a percent)	0.650
Percentage on limitation of debt to total capitalization under covenant (as a percent)	60.60%
Parent Company \| Line of Credit \| SOFR Plus
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)	1.50%
SIGECO
Debt Instrument [Line Items]
Aggregate principal amount	$ 250
SIGECO \| Line of Credit
Debt Instrument [Line Items]
Ratio of indebtedness to net capital (as a percent)	0.650
Percentage on limitation of debt to total capitalization under covenant (as a percent)	47.00%
SIGECO \| Line of Credit \| SOFR Plus
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)	1.125%

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

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- Definition

Percentage on limitation of debt to total capitalization under covenant.

+ References

No definition available.

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- Definition

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

+ References

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- Definition

Restoration Costs

+ References

No definition available.

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- Definition

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

+ References

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+ References

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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.

+ 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
-Subparagraph (SX 210.5-02.19(b),22(b))
-URI https://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

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- Definition

Indebtedness divided by net capital.

+ References

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