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Consecutive Period for System Restoration Costs to Exceed $100 million (in months)

No definition available.

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Credit facility swing line sublimit.

No definition available.

Name:	cnp_Creditfacilityswinglinesublimit
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Letters of credit swing line sublimit

No definition available.

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Amount of long-term debt, noncurrent portion, before deduction of unamortized discount or premium. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt, with initial maturities beyond one year or the normal operating cycle, if longer.

No definition available.

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Make-whole premium

No definition available.

Name:	cnp_Makewholepremium
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Maximum number of days until maturity of commercial paper issued in connection with the Merger.

No definition available.

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Number of days until commercial paper maturity.

No definition available.

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Percentage on limitation of debt to total capitalization under covenant.

No definition available.

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Percentage of property additions

No definition available.

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Temporary increased percentage on limitation of debt to total capitalization under covenant (in hundredths)

No definition available.

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This element represents those amounts to be set aside for the repair and replacement of real or personal property in the foreseen future. Such amount may be satisfied by certification of property additions.

No definition available.

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The minimum amount of estimated restoration cost in a calendar year in order for a temporary increase in debt to EBITDA covenant

No definition available.

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Amount to be paid in following year into the sinking fund. Such amount may be satisfied by certification of property additions.

No definition available.

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Weighted average interest rate of commercial paper issued in connection with the Merger.

No definition available.

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Percentage points added to the reference rate to compute the variable rate on the debt instrument.

No definition available.

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

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

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Weighted average interest rate of debt outstanding.

No definition available.

Name:	us-gaap_DebtWeightedAverageInterestRate
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Gross amount of debt extinguished.

No definition available.

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Balance Type:	debit
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The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

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Period Type:	instant

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No definition available.

Name:	us-gaap_LineOfCreditFacilityAbstract
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Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

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Data Type:	xbrli:monetaryItemType
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- References

No definition available.

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Amount of long-term debt payable, sinking fund requirements, and other securities issued that are redeemable by holder at fixed or determinable prices and dates maturing in the next fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of long-term debt payable, sinking fund requirements, and other securities issued that are redeemable by holder at fixed or determinable prices and dates maturing in the fifth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

Name:	us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFive
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Period Type:	instant

Amount of long-term debt payable, sinking fund requirements, and other securities issued that are redeemable by holder at fixed or determinable prices and dates maturing in the fourth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

Name:	us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour
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Amount of long-term debt payable, sinking fund requirements, and other securities issued that are redeemable by holder at fixed or determinable prices and dates maturing in the third fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of long-term debt payable, sinking fund requirements, and other securities issued that are redeemable by holder at fixed or determinable prices and dates maturing in the second fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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

Indebtedness divided by net capital.

No definition available.

Name:	us-gaap_RatioOfIndebtednessToNetCapital1
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Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

Carrying value as of the balance sheet date, including the current and noncurrent portions, of collateralized debt obligations (with maturities initially due after one year or beyond the operating cycle, if longer). Such obligations include mortgage loans, chattel loans, and any other borrowings secured by assets of the borrower.

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Name:	us-gaap_SecuredDebt
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
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Namespace Prefix:
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Name:	dei_LegalEntityAxis=cnp_HoustonElectricMember
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Data Type:	na
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Name:	us-gaap_LongtermDebtTypeAxis=cnp_BondsFirstMortgageDue2021Member
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