Contingencies and Commitments (Narrative) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2024 USD ($) MW $ / MWh facility	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)
Loss Contingencies [Line Items]
Environmental Loss Contingency, Statement Of Financial Position, Extensible Enumeration, Not Disclosed Flag	recorded liability
Regulatory assets	$ 3,569	$ 3,683
Consumers Energy Company
Loss Contingencies [Line Items]
Regulatory assets	$ 3,569	3,683
Consumers Energy Company | MCV PPA
Loss Contingencies [Line Items]
PPA maximum quantity required | MW	1,240
PPA fixed energy charge per MWh, on-peak (in dollars per MWh) | $ / MWh	6.30
PPA fixed energy charge per MWh, off-peak (in dollars per MWh) | $ / MWh	6.00
Annual contribution to renewable resources program by counterparty	$ 5
Purchases	$ 358	340	$ 519
Consumers Energy Company | MCV PPA | Year End Through March 2025
Loss Contingencies [Line Items]
PPA capacity charge per MWh (in dollars per MWh) | $ / MWh	10.14
Consumers Energy Company | MCV PPA | March 2025 Through Termination
Loss Contingencies [Line Items]
PPA capacity charge per MWh (in dollars per MWh) | $ / MWh	5.00
Consumers Energy Company | Other PPAs
Loss Contingencies [Line Items]
Purchases	$ 565	498	510
Consumers Energy Company | MGP sites
Loss Contingencies [Line Items]
Regulatory assets	$ 90	$ 99
Consumers Energy Company | Ludington
Loss Contingencies [Line Items]
Ownership share	51.00%
Consumers Energy Company | Ludington Plant Overhaul Contract Dispute
Loss Contingencies [Line Items]
Damages sought			15
Estimate of shared costs	$ 350
Consumers Energy Company | J.H. Campbell 3 Plant Retirement Contract Dispute
Loss Contingencies [Line Items]
Damages sought			$ 37
Bay Harbor
Loss Contingencies [Line Items]
Accrual for environmental loss contingencies	$ 48
Discount rate	4.34%
Accrual for environmental loss contingencies, inflation rate	1.00%
Accrual for environmental loss contingencies, gross	$ 61
NREPA | Electric Utility | Consumers Energy Company
Loss Contingencies [Line Items]
Accrual for environmental loss contingencies	4
NREPA | Minimum | Electric Utility | Consumers Energy Company
Loss Contingencies [Line Items]
Remediation and other response activity costs	4
NREPA | Maximum | Electric Utility | Consumers Energy Company
Loss Contingencies [Line Items]
Remediation and other response activity costs	5
CERCLA Liability | Consumers Energy Company
Loss Contingencies [Line Items]
Accrual for environmental loss contingencies	3
CERCLA Liability | Minimum | Consumers Energy Company
Loss Contingencies [Line Items]
Remediation and other response activity costs	3
CERCLA Liability | Maximum | Consumers Energy Company
Loss Contingencies [Line Items]
Remediation and other response activity costs	8
MGP sites | Consumers Energy Company
Loss Contingencies [Line Items]
Accrual for environmental loss contingencies	$ 60
Number of former MGPs | facility	23
Regulatory asset collection period	10 years