Regulatory Matters (Narrative) (Details) $ in Millions	1 Months Ended							12 Months Ended
	Jul. 31, 2024 USD ($)	May 31, 2024 USD ($)	Apr. 30, 2024 USD ($)	Mar. 31, 2024 USD ($)	Dec. 31, 2023 USD ($)	Sep. 30, 2023 USD ($)	May 31, 2023 USD ($)	Dec. 31, 2024 USD ($) facility	Mar. 31, 2024 USD ($)	Dec. 31, 2023 USD ($)	Mar. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2016 unit	Dec. 31, 2015 unit	Dec. 31, 2013 USD ($)	Nov. 30, 2024 USD ($)	Jun. 30, 2024 USD ($)	Nov. 30, 2023 USD ($)
Public Utilities, General Disclosures [Line Items]
Operating Revenue								$ 7,515.0		$ 7,462.0		$ 8,596.0
Regulatory assets					$ 3,683.0			3,569.0		3,683.0
Settlement agreement penalty payment		$ 1.0
Minimum settlement returns to customers		3.0
ASP gain
Public Utilities, General Disclosures [Line Items]
Gain on disposition of assets			$ 110.0
Amount credited to customers	$ 82.5
Consumers Energy Company
Public Utilities, General Disclosures [Line Items]
Operating Revenue								7,200.0		7,166.0		8,151.0
Regulatory assets					3,683.0			3,569.0		3,683.0
Purchased and interchange power								1,285.0		1,331.0		1,867.0
Cost of gas sold								$ 637.0		897.0		1,243.0
Consumers Energy Company | Renewable energy grant
Public Utilities, General Disclosures [Line Items]
Proceeds from government grant															$ 69.0
Consumers Energy Company | MGP sites
Public Utilities, General Disclosures [Line Items]
Number of former MGPs | facility								23
Regulatory asset collection period								10 years
Consumers Energy Company | Gas-Fueled Electric Generation
Public Utilities, General Disclosures [Line Items]
Number of units retired | unit														3
Consumers Energy Company | Coal-Fueled Electric Generation
Public Utilities, General Disclosures [Line Items]
Number of units retired | unit													7
Consumers Energy Company | Energy Waste Reduction Plan Incentive
Public Utilities, General Disclosures [Line Items]
Regulatory assets					58.0			$ 64.0		58.0
Consumers Energy Company | J.H. Campbell Generating Units
Public Utilities, General Disclosures [Line Items]
Regulatory assets												$ 1,300.0
Rate of return on equity authorized												9.00%
PSCR underrecoveries | Consumers Energy Company
Public Utilities, General Disclosures [Line Items]
PSCR underrecoveries												$ 401.0
Purchased and interchange power										1,800.0		$ 2,500.0
Over (under) recovery for gas fuel and power supply costs requested				$ (255.0)					$ (255.0)		$ (404.0)
PSCR underrecoveries | Consumers Energy Company | Revision of Prior Period, Adjustment
Public Utilities, General Disclosures [Line Items]
Over (under) recovery for gas fuel and power supply costs requested																		$ (401.0)
Energy Waste Reduction Plan Incentive | Consumers Energy Company
Public Utilities, General Disclosures [Line Items]
Authorized recovery collection																$ 58.0
Operating Revenue								$ 64.0		$ 58.0
Gas Rate Case | Consumers Energy Company
Public Utilities, General Disclosures [Line Items]
Rate of return on equity authorized	9.90%
Requested annual rate increase					$ 136.0
Requested annual rate increase, as a percent					10.25%
Amended requested annual rate increase		$ 113.0
Additional annual rate increase authorized	$ 35.0
Effective rate relief	62.5
Gas Rate Case | Consumers Energy Company | ASP gain
Public Utilities, General Disclosures [Line Items]
Gain on sale utilized as offset	$ 27.5
Electric Rate Case | Consumers Energy Company
Public Utilities, General Disclosures [Line Items]
Rate of return on equity authorized				9.90%
Requested annual rate increase							$ 216.0
Requested annual rate increase, as a percent							10.25%
Amended requested annual rate increase						$ 169.0
Additional annual rate increase authorized				$ 92.0
Surcharge for the recovery of excess distribution investments				9.0
GCR underrecoveries | Consumers Energy Company
Public Utilities, General Disclosures [Line Items]
Over (under) recovery for gas fuel and power supply costs requested				$ (15.0)					(15.0)								$ 3.0
Cost of gas sold									$ 500.0		$ 1,100.0