Commitments and Contingencies (Details)	3 Months Ended
Mar. 31, 2020 USD ($) site
Purchase Obligations
Remaining nine months of 2020	$ 464,000,000
2021	601,000,000
2022	409,000,000
2023	327,000,000
2024	263,000,000
2025	208,000,000
2026 and beyond	$ 1,622,000,000
Performance Guarantees & Product Warranties [Abstract]
Number of surety bond obligations outstanding	62
Performance guarantee obligations outstanding face amount	$ 563,000,000
Percentage of work yet to be completed on projects with open surety bonds	34.00%
Guarantor obligations, maximum exposure, undiscounted	$ 513,000,000
Minnesota and Indiana Gas Service Territories [Member]
Legal, Environmental and Other Matters
Liability recorded for environmental loss contingencies	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
CERC Corp [Member]
Purchase Obligations
Remaining nine months of 2020	$ 309,000,000
2021	417,000,000
2022	234,000,000
2023	175,000,000
2024	168,000,000
2025	163,000,000
2026 and beyond	1,329,000,000
CERC Corp [Member] \| Minnesota and Indiana Gas Service Territories [Member]
Legal, Environmental and Other Matters
Liability recorded for environmental loss contingencies	7,000,000
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	$ 69,000,000
Indiana Electric Integrated [Member] \| Minimum [Member]
Legal, Environmental and Other Matters
Estimated capital expenditure to clean ash ponds	60,000,000
Indiana Electric Integrated [Member] \| Maximum [Member]
Legal, Environmental and Other Matters
Estimated capital expenditure to clean ash ponds	80,000,000
Minnehaha Academy Gas Explosion [Member]
Legal, Environmental and Other Matters
Contested amount of fines imposed	200,000
Minnehaha Academy Gas Explosion [Member] \| CERC Corp [Member]
Legal, Environmental and Other Matters
Contested amount of fines imposed	200,000
Discontinued Operations [Member] \| CES natural gas related transactions [Member] \| CERC Corp [Member]
Performance Guarantees & Product Warranties [Abstract]
Performance guarantee obligations outstanding face amount	$ 1,500,000,000
Annualized fee received for retained CES obligation guarantees	3.00%
Quarterly increase of fee received for retained CES guarantee exposure	1.00%
Guarantor Obligations, Current Carrying Value	$ 0

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

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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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