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v3.21.2

Regulatory Matters - Quarterly Narrative (Details) - USD ($) $ in Millions | 3 Months Ended | 9 Months Ended | 12 Months Ended
--- | --- | --- | ---
Sep. 30, 2021 | Sep. 30, 2020 | Sep. 30, 2021 | Sep. 30, 2020 | Dec. 31, 2020
Public Utilities, General Disclosures [Line Items] |  |  |  |  |
Regulatory liabilities | $ 191 |  | $ 191 |  | $ 151
Operating Revenue | 1,725 | $ 1,507 | 5,296 | $ 4,691 |
Consumers Energy Company |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |
Regulatory liabilities | 191 |  | 191 |  | 151
Operating Revenue | 1,644 | $ 1,450 | 5,074 | $ 4,524 |
Consumers Energy Company | Reserve for customer refunds |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |
Regulatory liabilities | 8 |  | 8 |  | 28
Consumers Energy Company | Gain shared with customers |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |
Regulatory liabilities |  |  |  |  | 14
Consumers Energy Company | Electric Rate Case |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |
Recommended disallowed costs | 39 |  | 39 |  |
Consumers Energy Company | Energy Waste Reduction Plan Incentive |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |
Requested recovery/collection | $ 42 |  | $ 42 |  |
Operating Revenue |  |  |  |  | $ 42

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