Commitments and Contingencies - Narrative (Details) $ in Millions			9 Months Ended
	Jun. 08, 2023 USD ($)	Feb. 01, 2023 MW	Sep. 30, 2023 USD ($) gasManufacturingAndStorageSite lawsuit ashPond day	Feb. 28, 2023 lawsuit class	Jan. 11, 2023 MW
Long-Term Purchase Commitment [Line Items]
Guarantor obligations, maximum exposure, undiscounted | $			$ 509
Number of owned coal ash ponds | ashPond			3
Estimated project costs | $	$ 52
F.B. Culley
Long-Term Purchase Commitment [Line Items]
Number of owned coal ash ponds | ashPond			2
A.B. Brown
Long-Term Purchase Commitment [Line Items]
Number of owned coal ash ponds | ashPond			1
F.B. Culley East
Long-Term Purchase Commitment [Line Items]
Number of owned coal ash ponds | ashPond			1
Indiana Gas Service Territory
Long-Term Purchase Commitment [Line Items]
Environmental remediation number of sites with potential remedial responsibility | gasManufacturingAndStorageSite			26
SIGECO
Long-Term Purchase Commitment [Line Items]
Environmental remediation number of sites with potential remedial responsibility | gasManufacturingAndStorageSite			5
CERC | Indiana Gas Service Territory
Long-Term Purchase Commitment [Line Items]
Environmental remediation number of sites with potential remedial responsibility | gasManufacturingAndStorageSite			26
Indiana Electric
Long-Term Purchase Commitment [Line Items]
Asset retirement obligation | $			$ 116
Indiana Electric | Minimum
Long-Term Purchase Commitment [Line Items]
Estimated capital expenditure to clean ash ponds | $			60
Indiana Electric | Maximum
Long-Term Purchase Commitment [Line Items]
Estimated capital expenditure to clean ash ponds | $			$ 80
Loss from Catastrophes
Long-Term Purchase Commitment [Line Items]
Pending lawsuits				12
Loss from Catastrophes | Harris County
Long-Term Purchase Commitment [Line Items]
Pending lawsuits				9
Texas State Court in Harris County, Texas | Pending Litigation
Long-Term Purchase Commitment [Line Items]
Pending lawsuits			1
Bellwether Cases | Pending Litigation
Long-Term Purchase Commitment [Line Items]
Pending lawsuits			5
February 2021 Winter Storm Event | Utility Holding, LLC
Long-Term Purchase Commitment [Line Items]
Pending lawsuits | day			5
February 2021 Winter Storm Event | Loss from Catastrophes
Long-Term Purchase Commitment [Line Items]
Pending lawsuits			220
February 2021 Winter Storm Event | Loss from Catastrophes | CenterPoint Energy and Houston Electric
Long-Term Purchase Commitment [Line Items]
Pending lawsuits			155
Harris County vs. CERC - Putative | Loss from Catastrophes
Long-Term Purchase Commitment [Line Items]
Pending lawsuits				1
Number of classes of electric and natural gas customers | class				2
Other Texas Lawsuits Brought By Assignee vs. Company | Loss from Catastrophes
Long-Term Purchase Commitment [Line Items]
Pending lawsuits				2
Other Texas Lawsuits Brought By Assignee vs. Company | Loss from Catastrophes | Harris County
Long-Term Purchase Commitment [Line Items]
Pending lawsuits				1
Other Texas Lawsuits Brought By Assignee vs. Company | Loss from Catastrophes | Tom Green County
Long-Term Purchase Commitment [Line Items]
Pending lawsuits				1
Multi District Litigation | Cases Transferred to the Multi District Litigation (MDL)
Long-Term Purchase Commitment [Line Items]
Pending lawsuits			3
Multi District Litigation | Motions to Remand Lawsuits Out Of MDL And Back Into Original Trial Courts
Long-Term Purchase Commitment [Line Items]
Pending lawsuits			3
Posey Solar
Long-Term Purchase Commitment [Line Items]
Solar array generating capacity (in MW) | MW		191
Solar array assets, useful life		35 years
Pike Solar
Long-Term Purchase Commitment [Line Items]
Solar array generating capacity (in MW) | MW					130