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Acquisitions, Discontinued Operations and Dispositions - Acquisitions (Details) customer in Thousands, $ in Millions |  |  |  | 1 Months Ended | 12 Months Ended |
--- | --- | --- | --- | --- | --- | ---
Jan. 05, 2021 USD ($) customer state | Sep. 29, 2020 USD ($) | Aug. 01, 2019 USD ($) customer state | Dec. 31, 2020 USD ($) | Dec. 31, 2021 USD ($) | Dec. 31, 2020 USD ($) | Dec. 31, 2019 USD ($) | Jan. 05, 2021 province
Business Acquisition [Line Items] |  |  |  |  |  |  |  |
Number of states in which the entity operates | state |  |  | 9 |  |  |  |  |
Acquisition costs |  |  |  |  | $ 25 |  |  |
Revenues |  |  |  |  | 26,989 | $ 9,093 | $ 9,821 |
Income from continuing operations before income taxes |  |  |  |  | 2,859 | 761 | 786 |
Operating lease liability |  |  |  |  | 317 |  |  |
Joliet facility |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |
Lease expense |  |  |  |  |  |  | $ 14 |
Operating lease liability |  | $ 148 |  |  |  |  |  |
Powerton Facility And Units 7 And 8 Of The Joliet Facility |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |
Purchase of assets |  | $ 260 |  |  |  |  |  |
Direct Energy |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |
Customers added (over) | customer | 3,000 |  |  |  |  |  |  |
Purchase price | $ 3,625 |  |  |  |  |  |  |
Purchase price adjustment | 77 |  |  |  | 22 |  |  |
Cash paid to acquire business | 715 |  |  |  |  |  |  |
Proceeds from revolving credit facility | 166 |  |  |  |  |  |  |
Acquisition costs | $ 107 |  |  |  |  | $ 17 |  |
Proceeds from issuance of secured and unsecured corporate debt |  |  |  | $ 2,900 |  |  |  |
Revenues |  |  |  |  | 15,600 |  |  |
Income from continuing operations before income taxes |  |  |  |  | $ 2,400 |  |  |
Direct Energy | Customer Relationships |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |
Intangible assets, useful life | 12 years |  |  |  |  |  |  |
Direct Energy | Customer and Supply Contracts |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |
Intangible assets, useful life | 14 years |  |  |  |  |  |  |
Direct Energy | Trade Names |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |
Intangible assets, useful life | 15 years |  |  |  |  |  |  |
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
Stream Energy |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |
Cash paid to acquire business |  |  | $ 329 |  |  |  |  |
Working capital adjustments |  |  | $ 29 |  |  |  |  |
Residential customer equivalents acquired | customer |  |  | 600 |  |  |  |  |
Customers acquired | customer |  |  | 450 |  |  |  |  |

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