Annualized fee received for retained CES obligation guarantees

No definition available.

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- Definition

Contested amount of fines imposed by the Minnesota Office of Pipeline Safety.

+ References

No definition available.

+ Details

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Balance Type:	debit
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- Definition

Energy savings commitments not guaranteed

+ References

No definition available.

+ Details

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

- Definition

Number of sites identified where the entity may potentially have some remedial responsibility

+ References

No definition available.

+ Details

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Data Type:	xbrli:integerItemType
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- Definition

Estimated Remaining Exposure

+ References

No definition available.

+ Details

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Balance Type:	credit
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- Definition

Estimated Capital Expenditure to Clean Ash Ponds

+ References

No definition available.

+ Details

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

- Definition

Represents the number of warranties the wholly owned subsidiary has outstanding in its role as general contractor.

+ References

No definition available.

+ Details

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Data Type:	xbrli:integerItemType
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- Definition

Represents the absolute number of surety bonds the wholly owned subsidiary has outstanding in its role as general contractor

+ References

No definition available.

+ Details

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- Definition

Percentage of work yet to be completed by wholly owned subsidiary on projects with open surety bonds.

+ References

No definition available.

+ Details

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- Definition

Performance Guarantees & Product Warranties [Abstract]

+ References

No definition available.

+ Details

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- Definition

Face amount of individual surety bonds the wholly-owned subsidiary has outstanding

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
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- Definition

Quarterly increase of fee received for retained CES guarantee exposure

+ References

No definition available.

+ Details

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Data Type:	num:percentItemType
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- Definition

Estimate of the reasonably possible loss exposure at an individual site.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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- Definition

This represents the estimated years necessary to resolve the contingency.

+ References

No definition available.

+ Details

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Data Type:	us-types:durationStringItemType
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- Definition

Warranty obligations outstanding face amount

+ References

No definition available.

+ Details

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Namespace Prefix:	cnp_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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- Definition

Total costs accrued as of the balance sheet date for environmental loss contingencies.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
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-Topic 410
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Balance Type:	credit
Period Type:	instant

- Definition

The carrying amount of a liability for an asset retirement obligation. An asset retirement obligation is a legal obligation associated with the disposal or retirement of a tangible long-lived asset that results from the acquisition, construction or development, or the normal operations of a long-lived asset, except for certain obligations of lessees.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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-SubTopic 20
-Section 50
-Paragraph 1
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+ Details

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

- Definition

Maximum potential amount of future payments (undiscounted) the guarantor could be required to make under the guarantee or each group of similar guarantees before reduction for potential recoveries under recourse or collateralization provisions.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 460
-SubTopic 10
-Section 50
-Paragraph 4
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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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Data Type:	xbrli:stringItemType
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Period Type:	duration

- References

No definition available.

+ Details

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- Definition

Amount of purchase arrangement to be paid after fifth fiscal year following current fiscal year. Includes, but is not limited to, recorded and unrecorded purchase obligations, long-term purchase commitment, and short-term purchase commitment. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

+ References

No definition available.

+ Details

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- Definition

Amount of purchase arrangement to be paid in fifth fiscal year following current fiscal year. Includes, but is not limited to, recorded and unrecorded purchase obligations, long-term purchase commitment, and short-term purchase commitment. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

+ References

No definition available.

+ Details

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- Definition

Amount of purchase arrangement to be paid in fourth fiscal year following current fiscal year. Includes, but is not limited to, recorded and unrecorded purchase obligations, long-term purchase commitment, and short-term purchase commitment. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

+ References

No definition available.

+ Details

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- Definition

Amount of purchase arrangement to be paid in next fiscal year following current fiscal year. Includes, but is not limited to, recorded and unrecorded purchase obligations, long-term purchase commitment, and short-term purchase commitment. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

+ References

No definition available.

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- Definition

Amount of purchase arrangement to be paid in second fiscal year following current fiscal year. Includes, but is not limited to, recorded and unrecorded purchase obligations, long-term purchase commitment, and short-term purchase commitment. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

+ References

No definition available.

+ Details

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- Definition

Amount of purchase arrangement to be paid in third fiscal year following current fiscal year. Includes, but is not limited to, recorded and unrecorded purchase obligations, long-term purchase commitment, and short-term purchase commitment. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

+ References

No definition available.

+ Details

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- Details

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- Details

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Commitments and Contingencies (Details)	12 Months Ended
Commitments and Contingencies (Details)	Dec. 31, 2020 USD ($) site	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Guarantees & Product Warranties [Abstract]
Number of surety bond obligations outstanding	61
Performance guarantee obligations outstanding face amount	$ 610,000,000
Number of warranty obligations outstanding	31
Warranty obligations outstanding face amount	$ 558,000,000
Energy savings commitments not guaranteed	$ 1,200,000,000
Percentage of work yet to be completed on projects with open surety bonds	33.00%
Guarantor Obligations, Maximum Exposure, Undiscounted	$ 518,000,000
Legal, Environmental and Other Matters
Asset Retirement Obligation	787,000,000	$ 539,000,000	$ 258,000,000
Natural Gas and Coal
Purchase Obligations
2021	708,000,000
2022	542,000,000
2023	465,000,000
2024	387,000,000
2025	370,000,000
2026 and beyond	1,930,000,000
Technology Hardware and Software
Purchase Obligations
2021	17,000,000
2022	12,000,000
2023	10,000,000
2024	190,000,000
2025	0
2026 and beyond	$ 0
Indiana Gas Service Territory [Member]
Legal, Environmental and Other Matters
Environmental remediation number of sites with potential remedial responsibility \| site	26
Minnesota and Indiana Gas Service Territories [Member]
Legal, Environmental and Other Matters
Liability recorded for remediation of Minnesota sites	$ 12,000,000
Minnesota and Indiana Gas Service Territories [Member] \| Minimum [Member]
Legal, Environmental and Other Matters
Estimated remediation costs for the Minnesota sites	$ 7,000,000
Years to resolve contingency	5
Minnesota and Indiana Gas Service Territories [Member] \| Maximum [Member]
Legal, Environmental and Other Matters
Estimated remediation costs for the Minnesota sites	$ 54,000,000
Years to resolve contingency	50
SIGECO [Member]
Legal, Environmental and Other Matters
Environmental remediation number of sites with potential remedial responsibility \| site	5
Minnehaha Academy Gas Explosion [Member]
Legal, Environmental and Other Matters
Contested amount of fines imposed	$ 200,000
Indiana Electric [Member]
Legal, Environmental and Other Matters
Asset Retirement Obligation	74,000,000
Indiana Electric [Member] \| Minimum [Member]
Legal, Environmental and Other Matters
Estimated capital expenditure to clean ash ponds	60,000,000
Indiana Electric [Member] \| Maximum [Member]
Legal, Environmental and Other Matters
Estimated capital expenditure to clean ash ponds	80,000,000
CERC Corp [Member]
Legal, Environmental and Other Matters
Asset Retirement Obligation	571,000,000	$ 325,000,000	$ 221,000,000
CERC Corp [Member] \| Natural Gas and Coal
Purchase Obligations
2021	491,000,000
2022	328,000,000
2023	275,000,000
2024	254,000,000
2025	227,000,000
2026 and beyond	1,547,000,000
CERC Corp [Member] \| Minnesota and Indiana Gas Service Territories [Member]
Legal, Environmental and Other Matters
Liability recorded for remediation of Minnesota sites	7,000,000
CERC Corp [Member] \| Minnesota and Indiana Gas Service Territories [Member] \| Minimum [Member]
Legal, Environmental and Other Matters
Estimated remediation costs for the Minnesota sites	$ 4,000,000
Years to resolve contingency	30
CERC Corp [Member] \| Minnesota and Indiana Gas Service Territories [Member] \| Maximum [Member]
Legal, Environmental and Other Matters
Estimated remediation costs for the Minnesota sites	$ 32,000,000
Years to resolve contingency	50
CERC Corp [Member] \| Minnehaha Academy Gas Explosion [Member]
Legal, Environmental and Other Matters
Contested amount of fines imposed	$ 200,000
Energy Services Disposal Group [Member] \| CERC Corp [Member]
Guarantees & Product Warranties [Abstract]
Annualized fee received for retained CES obligation guarantees	3.00%
Quarterly increase of fee received for retained CES guarantee exposure	1.00%
Estimated Remaining Exposure	$ 61,000,000