Short-term Borrowings and Long-term Debt - Debt Transactions (Details) $ in Millions	9 Months Ended
Sep. 30, 2022 USD ($)
General Mortgage Bonds \| Houston Electric
Debt Instrument [Line Items]
Aggregate Principal Amount	$ 1,600
Senior Notes \| CERC
Debt Instrument [Line Items]
Aggregate Principal Amount	1,000
Senior Note and GMBs
Debt Instrument [Line Items]
Aggregate Principal Amount	2,600
General Mortgage Bonds 3.00% Due 2032 \| General Mortgage Bonds \| Houston Electric
Debt Instrument [Line Items]
Aggregate Principal Amount	$ 300
Interest rate of debt (as a percent)	3.00%
General Mortgage Bonds 3.60% Due 2052 \| General Mortgage Bonds \| Houston Electric
Debt Instrument [Line Items]
Aggregate Principal Amount	$ 500
Interest rate of debt (as a percent)	3.60%
General Mortgage Bonds 4.45% Due 2032 \| General Mortgage Bonds \| Houston Electric
Debt Instrument [Line Items]
Aggregate Principal Amount	$ 500
Interest rate of debt (as a percent)	4.45%
General Mortgage Bonds 4.85% Due 2052 \| General Mortgage Bonds \| Houston Electric
Debt Instrument [Line Items]
Aggregate Principal Amount	$ 300
Interest rate of debt (as a percent)	4.85%
CERC Senior Notes. 4.40% due 2032 \| Senior Notes \| CERC
Debt Instrument [Line Items]
Aggregate Principal Amount	$ 500
Interest rate of debt (as a percent)	4.40%
Proceeds from issuance of long-term debt, net of discounts and issuance expenses and fees	$ 495
CERC Senior Notes .70% due 2023 \| Term Loan \| CERC
Debt Instrument [Line Items]
Aggregate Principal Amount	500
Proceeds from issuance of long-term debt, net of discounts and issuance expenses and fees	$ 500
CERC Senior Notes .70% due 2023 \| Term Loan \| CERC \| SOFR
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)	0.70%
Adjustment to basis spread (as a percent)	0.10%
General Mortgage Bonds Issued In February 2022 \| General Mortgage Bonds \| Houston Electric
Debt Instrument [Line Items]
Proceeds from issuance of long-term debt, net of discounts and issuance expenses and fees	$ 784
General Mortgage Bonds Issued In September 2022 \| General Mortgage Bonds \| Houston Electric
Debt Instrument [Line Items]
Proceeds from issuance of long-term debt, net of discounts and issuance expenses and fees	$ 789

Debt Instrument, Basis Spread On Variable Rate, Adjustment

No definition available.

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

- Definition

Proceeds From Issuance Of Long-Term Debt, Net Of Discounts And Issuance Expenses And Fees

+ References

No definition available.

+ Details

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

- Definition

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

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 1B
-Subparagraph (a)
-URI https://asc.fasb.org/extlink&oid=123466505&loc=SL123495323-112611

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI https://asc.fasb.org/extlink&oid=124435984&loc=d3e28551-108399

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI https://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 50
-Paragraph 1
-URI https://asc.fasb.org/extlink&oid=124429444&loc=SL124452920-239629

Reference 5: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 55
-Paragraph 69C
-URI https://asc.fasb.org/extlink&oid=123466577&loc=SL123495737-112612

Reference 6: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 55
-Paragraph 69B
-URI https://asc.fasb.org/extlink&oid=123466577&loc=SL123495735-112612

+ Details

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

- Definition

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

+ References

+ Details

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

- 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

Name:	us-gaap_DebtInstrumentLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration