Related Party Transactions (Houston Electric and CERC) - Schedule of Transactions (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Houston Electric
Related Party Transaction [Line Items]
Cash dividends paid to parent	$ 0	$ 551	$ 376
Capital distribution	0	0	0
Property, plant and equipment from parent	0	36	0
Houston Electric \| Discontinued Operations
Related Party Transaction [Line Items]
Capital distribution	0	0	0
Houston Electric \| Additional Paid-in-Capital
Related Party Transaction [Line Items]
Cash contribution from parent	130	62	590
CERC Corp
Related Party Transaction [Line Items]
Cash dividends paid to parent	0	80	120
Capital distribution	0	0	28
Property, plant and equipment from parent	0	23	0
CERC Corp \| Discontinued Operations
Related Party Transaction [Line Items]
Capital distribution	0	286	0
CERC Corp \| Additional Paid-in-Capital
Related Party Transaction [Line Items]
Cash contribution from parent	$ 180	$ 217	$ 129

Contribution From Parent

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- Definition

The value of the noncash (or part noncash) consideration given (for example, liability, equity) in a transaction. Noncash is defined as transactions during a period that do not result in cash receipts or cash payments in the period. "Part noncash" refers to that portion of a transaction not resulting in cash receipts or cash payments in the period.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 50
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- Definition

Cash outflow in the form of capital distributions and dividends to common shareholders, preferred shareholders and noncontrolling interests.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
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-Section 45
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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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- Definition

Purchases during the period (excluding transactions that are eliminated in consolidated or combined financial statements) with related party.

+ References

No definition available.

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