v3.25.4

Fair Value Measurements (Summary of Assets and Liabilities Measured at Fair Value on a Recurring Basis) (Details) - USD ($) $ in Millions | Dec. 31, 2025 | Dec. 31, 2024
--- | --- | ---
Assets |  |
Restricted cash equivalents | $ 106 | $ 75
Consumers Energy Company |  |
Assets |  |
Restricted cash equivalents | 86 | 75
Fair Value, Inputs, Level 1, 2 and 3 |  |
Assets |  |
Total assets | 298 | 138
Liabilities |  |
Total liabilities | 39 | 34
Fair Value, Inputs, Level 1, 2 and 3 | Consumers Energy Company |  |
Assets |  |
Total assets | 115 | 102
Liabilities |  |
Total liabilities | 27 | 25
Fair Value, Inputs, Level 1 |  |
Assets |  |
Cash equivalents | 154 | 27
Restricted cash equivalents | 106 | 75
Nonqualified deferred compensation plan assets | 36 | 34
Liabilities |  |
Nonqualified deferred compensation plan liabilities | 36 | 34
Fair Value, Inputs, Level 1 | Consumers Energy Company |  |
Assets |  |
Cash equivalents | 0 | 0
Restricted cash equivalents | 86 | 75
Nonqualified deferred compensation plan assets | 27 | 25
Liabilities |  |
Nonqualified deferred compensation plan liabilities | 27 | 25
Fair Value, Inputs, Level 2 And Level 3 |  |
Assets |  |
Derivative instruments | 2 | 2
Liabilities |  |
Derivative instruments | 3 | 0
Fair Value, Inputs, Level 2 And Level 3 | Consumers Energy Company |  |
Assets |  |
Derivative instruments | 2 | 2
Liabilities |  |
Derivative instruments | $ 0 | $ 0

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