Capital Distribution to Parent Associated with the sale of CES

No definition available.

Name:	cnp_CapitalDistributionToParentAssociatedWithTheSaleOfCES
Namespace Prefix:	cnp_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Represents borrowings from the parent company's money pool.

+ References

No definition available.

+ Details

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Namespace Prefix:	cnp_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Represents investments in the parent company's money pool.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Weighted average interest rate of outstanding transactions in money pool.

+ References

No definition available.

+ Details

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Balance Type:	na
Period Type:	instant

- Definition

Amount of net service charges from (billings to) related party during the period, excluding transactions that are eliminated in consolidated or combined financial statements.

+ References

No definition available.

+ Details

Name:	cnp_Netaffiliateservicechargesbillings
Namespace Prefix:	cnp_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- 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
-SubTopic 10
-Section 45
-Paragraph 15
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=123570139&loc=d3e3291-108585

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- 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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Period Type:	duration

- Definition

Amount of selling, general and administrative expenses resulting from transactions, excluding transactions that are eliminated in consolidated or combined financial statements, with related party.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

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- Details

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- Details

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- Details

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- Details

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Related Party Transactions (Houston Electric and CERC) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Houston Electric
Related Party Transaction [Line Items]
Cash dividends paid to parent	$ 0	$ 20	$ 0	$ 405
Capital distribution to parent associated with the sale of CES	0	0	0	0
Houston Electric \| Operation and maintenance expense
Related Party Transaction [Line Items]
Net affiliate service charges (billings)	(1)	(4)	(2)	(10)
Houston Electric \| CenterPoint Energy \| Operation and maintenance expense
Related Party Transaction [Line Items]
Corporate service charges	47	45	90	94
CERC Corp
Related Party Transaction [Line Items]
Cash dividends paid to parent	0	40	0	72
Capital distribution to parent associated with the sale of CES	0	286	0	286
CERC Corp \| Operation and maintenance expense
Related Party Transaction [Line Items]
Net affiliate service charges (billings)	1	4	2	10
CERC Corp \| CenterPoint Energy \| Operation and maintenance expense
Related Party Transaction [Line Items]
Corporate service charges	$ 52	$ 49	$ 102	$ 104
Investments \| Houston Electric
Related Party Transaction [Line Items]
Weighted average interest rate	0.18%		0.18%		0.24%
Investments \| CERC Corp
Related Party Transaction [Line Items]
Weighted average interest rate	0.18%		0.18%		0.24%
Accounts and notes receivable (payable) - affiliate companies \| Houston Electric
Related Party Transaction [Line Items]
Money Pool Investments	$ 97		$ 97
Money Pool Borrowings					$ (8)
Accounts and notes receivable (payable) - affiliate companies \| CERC Corp
Related Party Transaction [Line Items]
Money Pool Investments	$ 0		$ 0		$ 0