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Financings And Capitalization (Narrative) (Details) - USD ($) | 1 Months Ended | 12 Months Ended |  |
--- | --- | --- | --- | ---
Aug. 31, 2018 | Dec. 31, 2018 | Dec. 28, 2018 | Dec. 31, 2017
Financing And Capitalization [Line Items] |  |  |  |
Limitation on payment of stock dividends |  | $ 4,800,000,000 |  |
Dividends paid |  | $ 531,000,000 |  |
Common stock authorized (in shares) |  | 350,000,000 |  | 350,000,000
Par value of common stock (in dollars per share) |  | $ 0.01 |  |
Preferred stock authorized (in shares) |  | 10,000,000 |  |
Par value of preferred stock (in dollars per share) |  | $ 0.01 |  |
Stock offering program maximum value | $ 250,000,000 | $ 100,000,000 |  |
Number of shares required to settle forward contracts (in shares) |  | 463 |  |
Consumers Energy Company |  |  |  |
Financing And Capitalization [Line Items] |  |  |  |
Unrestricted retained earnings |  | $ 1,300,000,000 |  |
Common stock authorized (in shares) |  | 125,000,000 |  | 125,000,000
Interest rate coverage ratio multiplier minimum to issue FMBs |  | 200.00% |  |
Consumers Energy Company | Commercial Paper |  |  |  |
Financing And Capitalization [Line Items] |  |  |  |
Short-term debt authorized borrowings |  | $ 500,000,000 |  |
Short-term borrowings outstanding |  | $ 97,000,000 |  |
Weighted average annual interest rate |  | 2.913% |  |
Term loans and revolving credit agreements |  |  |  |
Financing And Capitalization [Line Items] |  |  |  |
Amount of Facility |  |  | $ 300,000,000 |

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