Regulatory Matters - Narrative (Details) $ in Millions				12 Months Ended
	Apr. 05, 2023 USD ($)	Mar. 23, 2023 USD ($)	Jul. 01, 2022 USD ($)	Dec. 31, 2021 lease	Sep. 30, 2023 USD ($)	Jun. 29, 2023 USD ($)	Mar. 24, 2023 USD ($)	Jan. 04, 2023 USD ($)	Dec. 31, 2022 USD ($)	Oct. 19, 2022 USD ($)
Regulatory Assets [Line Items]
Regulatory assets current					$ 217				$ 1,385
Regulatory assets noncurrent					2,481				2,193
Disallowance of regulatory asset					53
Regulatory liability, approximate total gas cost					18				18
Regulatory asset remaining to recover through rates amount					5				11
CERC
Regulatory Assets [Line Items]
Regulatory assets current					205				1,336
Regulatory assets noncurrent					833				844
Regulatory liability, approximate total gas cost					17				17
Regulatory asset remaining to recover through rates amount					4				10
Houston Electric
Regulatory Assets [Line Items]
Regulatory assets noncurrent					775				778
Disallowance of regulatory asset					53
Number of leases entered into | lease				2
Subsidiaries | SIGECO
Regulatory Assets [Line Items]
Regulatory asset, authorized issuance costs							$ 341
Regulatory asset, issued						$ 341
Minnesota Public Utility Commission | CERC
Regulatory Assets [Line Items]
Disallowance of regulatory asset										$ 36
Attorney General's Office | CERC
Regulatory Assets [Line Items]
Regulatory assets										$ 409
IURC
Regulatory Assets [Line Items]
Regulatory asset, authorized issuance costs								$ 350
Public Utility Commission Of Texas | Houston Electric | TEEEF Lease One
Regulatory Assets [Line Items]
Recovery of deferred costs sought			$ 200
Annual revenue increase from lease agreements			$ 57
Regulatory asset, revenue requirement amount	$ 39
Regulatory asset, amortization period	82 months 15 days
Public Utility Commission Of Texas | Houston Electric | TEEEF Lease Two
Regulatory Assets [Line Items]
Annual revenue increase from lease agreements	$ 149
Regulatory asset, revenue requirement amount	$ 188
Regulatory asset, amortization period	78 months
February 2021 Winter Storm
Regulatory Assets [Line Items]
Regulatory assets current					92
February 2021 Winter Storm | REP Bad Debt Expense
Regulatory Assets [Line Items]
Regulatory assets					8				8
February 2021 Winter Storm | Operation and maintenance expense
Regulatory Assets [Line Items]
Regulatory assets					17				16
February 2021 Winter Storm | CERC
Regulatory Assets [Line Items]
Regulatory assets current					92
Regulatory assets noncurrent					141
February 2021 Winter Storm | Houston Electric | REP Bad Debt Expense
Regulatory Assets [Line Items]
Regulatory assets					8				8
February 2021 Winter Storm | Houston Electric | Operation and maintenance expense
Regulatory Assets [Line Items]
Regulatory assets					17				16
February 2021 Winter Storm Event
Regulatory Assets [Line Items]
Regulatory asset, approximate total gas cost					2,000
Regulatory assets current									1,175
Regulatory assets noncurrent					141				202
Regulatory liability, amount remaining under prudence review					$ 75
February 2021 Winter Storm Event | CERC
Regulatory Assets [Line Items]
Regulatory assets current									1,175
Regulatory assets noncurrent									$ 202
February 2021 Winter Storm Event | Customer Rate Relief Bond Financing
Regulatory Assets [Line Items]
Cash proceeds received from government grants		$ 1,100