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Contingencies and Commitments (Narrative) (Details) $ in Millions | 12 Months Ended
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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 |  |

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