v3.25.4
Contingencies and Commitments (Narrative) (Details)
$ in Millions
 1 Months Ended 12 Months Ended
Dec. 31, 2025
USD ($)
MW
facility
Sep. 30, 2025
MW
$ / MWh
Dec. 31, 2025
USD ($)
MW
$ / MWh
facility
Dec. 31, 2024
USD ($)
Dec. 31, 2023
USD ($)
Dec. 31, 2022
USD ($)
Loss Contingencies [Line Items]            
Environmental Loss Contingency, Statement Of Financial Position, Extensible Enumeration, Not Disclosed Flag     recorded liability      
Regulatory assets $ 3,355   $ 3,355 $ 3,569    
Consumers Energy Company            
Loss Contingencies [Line Items]            
Regulatory assets $ 3,355   $ 3,355 3,569    
Consumers Energy Company | MCV PPA            
Loss Contingencies [Line Items]            
PPA maximum quantity required | MW 1,240 1,240 1,240      
PPA capacity charge per MWh (in dollars per MWh) | $ / MWh   5.00        
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     $ 360 358 $ 340  
Purchase obligation term   10 years        
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     $ 603 565 $ 498  
Consumers Energy Company | MGP sites            
Loss Contingencies [Line Items]            
Regulatory assets $ 82   82 $ 90    
Consumers Energy Company | Ludington Plant Overhaul Contract Dispute            
Loss Contingencies [Line Items]            
Damages sought           $ 15
Damages awarded 383          
Additional damages awarded 11          
Estimate of shared costs 350   350      
Bay Harbor            
Loss Contingencies [Line Items]            
Accrual for environmental loss contingencies $ 48   $ 48      
Discount rate 4.34%   4.34%      
Accrual for environmental loss contingencies, inflation rate 1.00%   1.00%      
Accrual for environmental loss contingencies, gross $ 62   $ 62      
NREPA | Electric Utility | Consumers Energy Company            
Loss Contingencies [Line Items]            
Accrual for environmental loss contingencies 2   2      
NREPA | Minimum | Electric Utility | Consumers Energy Company            
Loss Contingencies [Line Items]            
Remediation and other response activity costs 2   2      
NREPA | Maximum | Electric Utility | Consumers Energy Company            
Loss Contingencies [Line Items]            
Remediation and other response activity costs 3   3      
CERCLA Liability | Consumers Energy Company            
Loss Contingencies [Line Items]            
Accrual for environmental loss contingencies 3   3      
CERCLA Liability | Minimum | Consumers Energy Company            
Loss Contingencies [Line Items]            
Remediation and other response activity costs 3   3      
CERCLA Liability | Maximum | Consumers Energy Company            
Loss Contingencies [Line Items]            
Remediation and other response activity costs 8   8      
MGP sites | Consumers Energy Company            
Loss Contingencies [Line Items]            
Accrual for environmental loss contingencies $ 59   $ 59      
Number of former MGPs | facility 23   23      
Regulatory asset collection period 10 years   10 years