Commitments and Contingencies (Details)	3 Months Ended	6 Months Ended
Jun. 30, 2020 USD ($) site	Jun. 30, 2020 USD ($) site
Purchase Obligations
Remaining six months of 2020	$ 356,000,000	$ 356,000,000
2021	669,000,000	669,000,000
2022	499,000,000	499,000,000
2023	390,000,000	390,000,000
2024	321,000,000	321,000,000
2025	266,000,000	266,000,000
2026 and beyond	$ 1,812,000,000	$ 1,812,000,000
Performance Guarantees & Product Warranties [Abstract]
Number of surety bond obligations outstanding	66	66
Performance guarantee obligations outstanding face amount	$ 564,000,000	$ 564,000,000
Percentage of work yet to be completed on projects with open surety bonds		26.00%
Guarantor obligations, maximum exposure, undiscounted	528,000,000	$ 528,000,000
Minnesota and Indiana Gas Service Territories [Member]
Legal, Environmental and Other Matters
Liability recorded for environmental loss contingencies	$ 11,000,000	11,000,000
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 years
Minnesota and Indiana Gas Service Territories [Member] \| Maximum [Member]
Legal, Environmental and Other Matters
Estimated remediation costs for the Minnesota sites		$ 53,000,000
Years to resolve contingency		50 years
Indiana Gas Service Territory [Member]
Legal, Environmental and Other Matters
Environmental remediation number of sites with potential remedial responsibility \| site	26	26
CERC Corp [Member]
Purchase Obligations
Remaining six months of 2020	$ 246,000,000	$ 246,000,000
2021	484,000,000	484,000,000
2022	321,000,000	321,000,000
2023	236,000,000	236,000,000
2024	224,000,000	224,000,000
2025	219,000,000	219,000,000
2026 and beyond	1,495,000,000	1,495,000,000
CERC Corp [Member] \| Minnesota and Indiana Gas Service Territories [Member]
Legal, Environmental and Other Matters
Liability recorded for environmental loss contingencies	7,000,000	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		$ 5,000,000
Years to resolve contingency		30 years
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 years
Indiana Electric Integrated [Member]
Legal, Environmental and Other Matters
Asset retirement obligation	72,000,000	$ 72,000,000
Indiana Electric Integrated [Member] \| Minimum [Member]
Legal, Environmental and Other Matters
Estimated capital expenditure to clean ash ponds	60,000,000	60,000,000
Indiana Electric Integrated [Member] \| Maximum [Member]
Legal, Environmental and Other Matters
Estimated capital expenditure to clean ash ponds	80,000,000	80,000,000
Minnehaha Academy Gas Explosion [Member]
Legal, Environmental and Other Matters
Contested amount of fines imposed	200,000	200,000
Minnehaha Academy Gas Explosion [Member] \| CERC Corp [Member]
Legal, Environmental and Other Matters
Contested amount of fines imposed	$ 200,000	$ 200,000
CES natural gas related transactions [Member] \| CERC Corp [Member]
Performance Guarantees & Product Warranties [Abstract]
Quarterly increase of fee received for retained CES guarantee exposure	3.00%
Quarterly increase of fee received for retained CES guarantee exposure	1.00%
Estimated Remaining Exposure	$ 103,000,000

Annualized fee received for retained CES obligation guarantees

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

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

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Estimated Remaining Exposure

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Estimated Capital Expenditure to Clean Ash Ponds

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

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

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Performance Guarantees & Product Warranties [Abstract]

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

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Quarterly increase of fee received for retained CES guarantee exposure

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

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This represents the estimated years necessary to resolve the contingency.

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

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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.

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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.

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Minimum amount of purchase arrangement maturing after the fifth fiscal year following the latest fiscal year. Includes, but not limited to, recorded and unrecorded purchase obligations, long-term purchase commitments, and short-term purchase commitments.

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Minimum amount of purchase arrangement maturing in the fifth fiscal year following the latest fiscal year. Includes, but not limited to, recorded and unrecorded purchase obligations, long-term purchase commitments, and short-term purchase commitments.

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Minimum amount of purchase arrangement maturing in the fourth fiscal year following the latest fiscal year. Includes, but not limited to, recorded and unrecorded purchase obligations, long-term purchase commitments, and short-term purchase commitments.

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Minimum amount of purchase arrangement maturing in the next fiscal year following the latest fiscal year. Includes, but not limited to, recorded and unrecorded purchase obligations, long-term purchase commitments, and short-term purchase commitments.

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Minimum amount of purchase arrangement maturing in the second fiscal year following the latest fiscal year. Includes, but not limited to, recorded and unrecorded purchase obligations, long-term purchase commitments, and short-term purchase commitments.

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Minimum amount of purchase arrangement maturing in the third fiscal year following the latest fiscal year. Includes, but not limited to, recorded and unrecorded purchase obligations, long-term purchase commitments, and short-term purchase commitments.

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Minimum amount of purchase arrangement maturing in the remainder of the fiscal year following the latest fiscal year ended. Includes, but is not limited to, recorded and unrecorded purchase obligations, long-term purchase commitments, and short-term purchase commitments.

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