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Contingencies and Commitments (Narrative) (Details) $ in Millions | 1 Months Ended | 12 Months Ended
--- | --- | ---
Jul. 31, 2022 USD ($) | Jun. 30, 2022 USD ($) | Dec. 31, 2023 USD ($) MW $ / MWh facility | Dec. 31, 2022 USD ($) | Dec. 31, 2021 USD ($)
Loss Contingencies [Line Items] |  |  |  |  |
Environmental Loss Contingency, Statement Of Financial Position, Extensible Enumeration, Not Disclosed Flag |  |  | recorded liability |  |
Regulatory assets |  |  | $ 3,683 | $ 3,595 |
Consumers Energy Company |  |  |  |  |
Loss Contingencies [Line Items] |  |  |  |  |
Regulatory assets |  |  | $ 3,683 | 3,595 |
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 |  |  | $ 340 | 519 | $ 348
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 |  |  | $ 498 | 510 | $ 338
Consumers Energy Company | MGP sites |  |  |  |  |
Loss Contingencies [Line Items] |  |  |  |  |
Regulatory assets |  |  | $ 99 | $ 108 |
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 |  |  |
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 |  |  | $ 45 |  |
Discount rate |  |  | 4.34% |  |
Accrual for environmental loss contingencies, inflation rate |  |  | 1.00% |  |
Accrual for environmental loss contingencies, gross |  |  | $ 57 |  |
NREPA | Electric Utility | Consumers Energy Company |  |  |  |  |
Loss Contingencies [Line Items] |  |  |  |  |
Accrual for environmental loss contingencies |  |  | 2 |  |
NREPA | Gas Utility | Consumers Energy Company |  |  |  |  |
Loss Contingencies [Line Items] |  |  |  |  |
Accrual for environmental loss contingencies |  |  | 1 |  |
NREPA | Minimum | Electric Utility | Consumers Energy Company |  |  |  |  |
Loss Contingencies [Line Items] |  |  |  |  |
Remediation and other response activity costs |  |  | 2 |  |
NREPA | Maximum | Electric Utility | Consumers Energy Company |  |  |  |  |
Loss Contingencies [Line Items] |  |  |  |  |
Remediation and other response activity costs |  |  | 4 |  |
NREPA | Maximum | Gas Utility | Consumers Energy Company |  |  |  |  |
Loss Contingencies [Line Items] |  |  |  |  |
Remediation and other response activity costs |  |  | 1 |  |
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 |  |  | $ 62 |  |
Number of former MGPs | facility |  |  | 23 |  |
Regulatory asset collection period |  |  | 10 years |  |

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