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v3.23.1

Contingencies and Commitments (Narrative) (Details) $ in Millions | 1 Months Ended | 3 Months Ended |
--- | --- | --- | ---
Jul. 31, 2022 USD ($) | Jun. 30, 2022 USD ($) | Mar. 31, 2023 USD ($) site | Dec. 31, 2022 USD ($)
Loss Contingencies [Line Items] |  |  |  |
Regulatory assets |  |  | $ 3,804 | $ 3,595
Environmental Loss Contingency, Statement Of Financial Position, Extensible Enumeration, Not Disclosed Flag |  |  | recorded liability |
Consumers Energy Company |  |  |  |
Loss Contingencies [Line Items] |  |  |  |
Regulatory assets |  |  | $ 3,804 | $ 3,595
Consumers Energy Company | MGP Sites |  |  |  |
Loss Contingencies [Line Items] |  |  |  |
Regulatory assets |  |  | $ 106 |
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 |  |  | $ 56 |
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 |  |  | 3 |
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 |  |  | $ 63 |
Discount rate |  |  | 2.57% |
Accrual for environmental loss contingencies, inflation rate |  |  | 2.50% |
Accrual for environmental loss contingencies, gross |  |  | $ 67 |
Number of former MGPs | site |  |  | 23 |
Regulatory asset collection period |  |  | 10 years |

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