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v3.20.2

Financings and Capitalization (Narrative) (Details) - USD ($) | 1 Months Ended | 9 Months Ended | 24 Months Ended |
--- | --- | --- | --- | ---
Oct. 29, 2020 | Sep. 30, 2020 | Apr. 30, 2020 | Mar. 31, 2020 | Sep. 30, 2020 | Sep. 30, 2019 | Dec. 31, 2019 | Jul. 31, 2020
Financing And Capitalization [Line Items] |  |  |  |  |  |  |  |
Principal balance |  | $ 2,334,000,000 |  |  | $ 2,334,000,000 |  |  |
Amount available for dividend payments |  | $ 5,300,000,000 |  |  | 5,300,000,000 |  |  |
Common stock dividends from Consumers |  |  |  |  | 449,000,000 |  |  |
Stock offering program maximum value |  |  | $ 500,000,000 |  |  |  |  |
Proceeds from settlement of forward contracts |  |  |  |  | $ 107,000,000 | $ 9,000,000 |  |
Settlement required (in shares) |  | 538,335 |  |  | 538,335 |  |  |
Consumers Energy Company |  |  |  |  |  |  |  |
Financing And Capitalization [Line Items] |  |  |  |  |  |  |  |
Principal balance |  | $ 1,534,000,000 |  |  | $ 1,534,000,000 |  |  |
Unrestricted retained earnings |  | 1,600,000,000 |  |  | 1,600,000,000 |  |  |
Consumers Energy Company | Commercial Paper |  |  |  |  |  |  |  |
Financing And Capitalization [Line Items] |  |  |  |  |  |  |  |
Short-term debt, authorized borrowings |  |  |  |  | 500,000,000 |  |  |
Short-term debt |  | 0 |  |  | $ 0 |  |  |
Forward Contracts |  |  |  |  |  |  |  |
Financing And Capitalization [Line Items] |  |  |  |  |  |  |  |
Forward sales contracts aggregate price |  | $ 52,000,000 |  |  |  |  | $ 250,000,000 |
Settlement of Forward Contracts |  |  |  |  |  |  |  |
Financing And Capitalization [Line Items] |  |  |  |  |  |  |  |
Settlement of forward contract issued (in shares) |  |  |  | 2,017,783 |  |  |  |
Forward contract settlement (in dollars per share) |  |  |  | $ 47.95 |  |  |  |
Proceeds from settlement of forward contracts |  |  |  | $ 97,000,000 |  |  |  |
Tax Exempt Revenue Bonds | Tax Exempt Revenue Bonds Due 2035 | Consumers Energy Company |  |  |  |  |  |  |  |
Financing And Capitalization [Line Items] |  |  |  |  |  |  |  |
Debt repurchased |  |  |  |  |  |  |  | $ 35,000,000
Subsequent Event | First Mortgage Bonds Due October 2070 | Consumers Energy Company |  |  |  |  |  |  |  |
Financing And Capitalization [Line Items] |  |  |  |  |  |  |  |
Principal balance | $ 127,000,000 |  |  |  |  |  |  |
London Interbank Offered Rate (LIBOR) | Subsequent Event | First Mortgage Bonds Due October 2070 | Consumers Energy Company |  |  |  |  |  |  |  |
Financing And Capitalization [Line Items] |  |  |  |  |  |  |  |
Basis spread on variable rate | 0.30% |  |  |  |  |  |  |
Interest rate floor | 0.00% |  |  |  |  |  |  |

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