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Nature of Business (Details) customer in Millions, $ in Millions |  |  |  | 12 Months Ended |  |  |
--- | --- | --- | --- | --- | --- | --- | ---
Dec. 06, 2021 USD ($) MW | Dec. 01, 2021 USD ($) MW | Jan. 05, 2021 customer state | Dec. 31, 2021 customer MW | Jun. 30, 2021 MW | Jan. 05, 2021 province | Aug. 01, 2019 state
Business Acquisition [Line Items] |  |  |  |  |  |  |
Generation capacity (in MW) |  |  |  | 18,000 |  |  |
Number of states in which the entity operates | state |  |  |  |  |  |  | 9
PJM Coal Generating Assets |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |
Generation capacity (in MW) |  |  |  |  | 1,600 |  |
East/West Other | Arthur Kill Plant |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |
Generation capacity (in MW) | 866 | 866 |  |  |  |  |
East/West Other | Disposal Group, Held-for-sale or Disposed of by Sale, Not Discontinued Operations |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |
Generation capacity (in MW) |  | 4,850 |  |  |  |  |
Proceeds from sale of, net of working capital adjustments | $ | $ 623 | $ 623 |  |  |  |  |
Direct Energy |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |
Customers served (over) | customer |  |  | 3 |  |  |  |
Direct Energy | U.S. |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |
Number of states in which the entity operates | state |  |  | 50 |  |  |  |
Direct Energy | Canada |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |
Provinces in which entity operates |  |  | 8 |  |  | 8 |
Home |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |
Customers served (over) | customer |  |  |  | 6 |  |  |

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