Fair Value Measurements - Schedule of Assets and Liabilities Measured On Recurring Basis (Details) - Fair Value, Measurements, Recurring - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Assets
Equity securities	$ 510	$ 1,439
Investments, including money market funds	32	42
Interest rate derivatives	1	0
Total assets	554	1,495
Liabilities
Total liabilities	578	917
Indexed debt securities derivative
Liabilities
Derivative Liability	578	903
Interest rate derivatives
Liabilities
Derivative Liability	0	14
Natural gas derivatives
Assets
Natural gas derivatives	11	14
Level 1
Assets
Equity securities	510	1,439
Investments, including money market funds	32	42
Interest rate derivatives	0	0
Total assets	542	1,481
Liabilities
Total liabilities	0	0
Level 1 \| Indexed debt securities derivative
Liabilities
Derivative Liability	0	0
Level 1 \| Interest rate derivatives
Liabilities
Derivative Liability	0	0
Level 1 \| Natural gas derivatives
Assets
Natural gas derivatives	0	0
Level 2
Assets
Equity securities	0	0
Investments, including money market funds	0	0
Interest rate derivatives	1	0
Total assets	12	14
Liabilities
Total liabilities	578	917
Level 2 \| Indexed debt securities derivative
Liabilities
Derivative Liability	578	903
Level 2 \| Interest rate derivatives
Liabilities
Derivative Liability	0	14
Level 2 \| Natural gas derivatives
Assets
Natural gas derivatives	11	14
Level 3
Assets
Equity securities	0	0
Investments, including money market funds	0	0
Interest rate derivatives	0	0
Total assets	0	0
Liabilities
Total liabilities	0	0
Level 3 \| Indexed debt securities derivative
Liabilities
Derivative Liability	0	0
Level 3 \| Interest rate derivatives
Liabilities
Derivative Liability	0	0
Level 3 \| Natural gas derivatives
Assets
Natural gas derivatives	0	0
Houston Electric
Assets
Investments, including money market funds	17	27
Total assets	17	27
Houston Electric \| Level 1
Assets
Investments, including money market funds	17	27
Total assets	17	27
Houston Electric \| Level 2
Assets
Investments, including money market funds	0	0
Total assets	0	0
Houston Electric \| Level 3
Assets
Investments, including money market funds	0	0
Total assets	0	0
CERC Corp
Assets
Investments, including money market funds	14	14
Total assets	23	26
CERC Corp \| Natural gas derivatives
Assets
Natural gas derivatives	9	12
CERC Corp \| Level 1
Assets
Investments, including money market funds	14	14
Total assets	14	14
CERC Corp \| Level 1 \| Natural gas derivatives
Assets
Natural gas derivatives	0	0
CERC Corp \| Level 2
Assets
Investments, including money market funds	0	0
Total assets	9	12
CERC Corp \| Level 2 \| Natural gas derivatives
Assets
Natural gas derivatives	9	12
CERC Corp \| Level 3
Assets
Investments, including money market funds	0	0
Total assets	0	0
CERC Corp \| Level 3 \| Natural gas derivatives
Assets
Natural gas derivatives	$ 0	$ 0

Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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Fair value, after the effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets not subject to a master netting arrangement and not elected to be offset.

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Amount of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).

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Fair value of financial obligations, including, but not limited to, debt instruments, derivative liabilities, federal funds purchased and sold under agreements to repurchase, securities loaned or sold under agreements to repurchase, financial instruments sold not yet purchased, guarantees, line of credit, loans and notes payable, servicing liability, and trading liabilities.

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Fair value portion of investment securities, including, but not limited to, marketable securities, derivative financial instruments, and investments accounted for under the equity method.

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