Asset Sales and Exit Activities - Narrative (Details) $ in Millions	1 Months Ended		3 Months Ended
	Sep. 30, 2019 USD ($)	Apr. 30, 2019 USD ($)	Dec. 31, 2019 USD ($) coal_fueled_electric_generating_unit	Oct. 24, 2019 USD ($)	Dec. 31, 2018 USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Regulatory liabilities			$ 87		$ 155
Other current liabilities			186		147
DIG's High-Voltage Equipment to ITC | Disposal Group, Held-for-sale or Disposed of by Sale, Not Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain on disposition of assets		$ 16
Electric Utility | Gain shared with customers | Disposal Group, Held-for-sale or Disposed of by Sale, Not Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain on disposition of assets	$ 17
Consumers Energy Company
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Regulatory liabilities			87		155
Other current liabilities			$ 118		120
Consumers Energy Company | Costs of coal-fueled electric generating units to be retired
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of units | coal_fueled_electric_generating_unit			2
D.E. Karn Generating Complex
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Expected cost				$ 35
Retention and Severance Benefits | D.E. Karn Generating Complex
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Retention and severance costs			$ 6
Other current liabilities			2
Gain shared with customers | Consumers Energy Company
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Regulatory liabilities			$ 17		$ 0