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

Number of shares attributable to each note and referenced in determining the fair value of the cash to be exchange at behest of note holder.

No definition available.

Name:	cnp_NumberOfSharesReferencedInExchangeableSubordinatedNote
Namespace Prefix:	cnp_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	instant

The percentage of the fair value of the referenced TW Common shares attributable to each note and the percentage of composite fair value each note can be exchanged for cash.

No definition available.

Name:	cnp_SubordinatedNoteCashExchangeablePercentageOfFairValue
Namespace Prefix:	cnp_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

The target annual yield from interest and cash dividends on reference shares, before any adjustment to increase or decrease principal amount of subordinated note is made.

No definition available.

Name:	cnp_TargetAnnualYieldOnReferenceShares
Namespace Prefix:	cnp_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

Face (par) amount of debt instrument at time of issuance.

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Contractual interest rate for funds borrowed, under the debt agreement.

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Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

Balance held at close of period in number of shares.

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

Percentage of subsidiary's or equity investee's stock owned by parent company after stock transaction.

No definition available.

Name:	us-gaap_SaleOfStockPercentageOfOwnershipAfterTransaction
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

Name:	dei_LegalEntityAxis=cnp_ATTIncMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_CommonStockMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	dei_LegalEntityAxis=cnp_CharterCommunicationsIncMember
Namespace Prefix:
Data Type:	na
Balance Type:
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