v3.26.1
Fair Value Measurements (Schedule of Assets and Liabilities Measured at Fair Value on a Recurring Basis) (Details) - USD ($)
$ in Millions
Jun. 30, 2026
Dec. 31, 2025
Assets    
Restricted cash equivalents $ 104 $ 106
Consumers Energy Company    
Assets    
Restricted cash equivalents 85 86
Fair Value, Inputs, Level 1, 2 and 3    
Assets    
Total assets 180 298
Liabilities    
Total liabilities 40 39
Fair Value, Inputs, Level 1, 2 and 3 | Consumers Energy Company    
Assets    
Total assets 117 115
Liabilities    
Total liabilities 29 27
Fair Value, Inputs, Level 1    
Assets    
Cash equivalents 35 154
Restricted cash equivalents 104 106
Nonqualified deferred compensation plan assets 38 36
Liabilities    
Nonqualified deferred compensation plan liabilities 38 36
Fair Value, Inputs, Level 1 | Consumers Energy Company    
Assets    
Cash equivalents 0 0
Restricted cash equivalents 85 86
Nonqualified deferred compensation plan assets 29 27
Liabilities    
Nonqualified deferred compensation plan liabilities 29 27
Fair Value, Inputs, Level 2 And Level 3    
Assets    
Derivative instruments 3 2
Liabilities    
Derivative instruments 2 3
Fair Value, Inputs, Level 2 And Level 3 | Consumers Energy Company    
Assets    
Derivative instruments 3 2
Liabilities    
Derivative instruments $ 0 $ 0