v3.19.1

Summary of Significant Accounting Policies (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016
Restricted Cash and Cash Equivalents Items [Line Items] |  |  |
Current | $ 167 | $ 134 |
Non-current | 34 | 25 |
Total | 201 | 159 |
Basis Of Presentation and Summary of Significant Accounting Policies (Textuals) [Abstract] |  |  |
Gain on Business Interruption Insurance Recovery | $ 14 | 27 | $ 24
Income Taxes Threshold Percentage | 50.00% |  |
Property, plant and equipment, salvage value (as a percent) | 10.00% |  |
Goodwill | $ 242 | 242 |
Impairment losses | 10 | 41 | 13
Asset retirement obligations | 63 | 43 |
Long-term Debt | 10,156 | 11,213 |
Property, Plant and Equipment, Net | $ 12,442 | 12,724 |
Jointly Owned Plants [Abstract] |  |  |
Goodwill, Purchase Accounting Adjustments |  | 6 |
Freestone Energy Center [Member] |  |  |
Jointly Owned Plants [Abstract] |  |  |
Jointly Owned Utility Plant, Proportionate Ownership Share | 75.00% |  |
Jointly Owned Utility Plant, Gross Ownership Amount of Plant in Service | $ 379 |  |
Jointly Owned Utility Plant, Ownership Amount of Plant Accumulated Depreciation | (167) |  |
Jointly Owned Utility Plant, Ownership Amount of Construction Work in Progress | $ 1 |  |
Hidalgo Energy Center [Member] |  |  |
Jointly Owned Plants [Abstract] |  |  |
Jointly Owned Utility Plant, Proportionate Ownership Share | 78.50% |  |
Jointly Owned Utility Plant, Gross Ownership Amount of Plant in Service | $ 251 |  |
Jointly Owned Utility Plant, Ownership Amount of Plant Accumulated Depreciation | (114) |  |
Jointly Owned Utility Plant, Ownership Amount of Construction Work in Progress | 4 |  |
Debt Service |  |  |
Restricted Cash and Cash Equivalents Items [Line Items] |  |  |
Current | 13 | 11 |
Non-current | 8 | 8 |
Total | 21 | 19 |
Construction Major Maintenance |  |  |
Restricted Cash and Cash Equivalents Items [Line Items] |  |  |
Current | 23 | 28 |
Non-current | 24 | 16 |
Total | 47 | 44 |
Security Project Insurance |  |  |
Restricted Cash and Cash Equivalents Items [Line Items] |  |  |
Current | 120 | 92 |
Non-current | 0 | 0 |
Total | 120 | 92 |
Other |  |  |
Restricted Cash and Cash Equivalents Items [Line Items] |  |  |
Current | 11 | 3 |
Non-current | 2 | 1 |
Total | $ 13 | 4 |
Greenfield [Member] |  |  |
Basis Of Presentation and Summary of Significant Accounting Policies (Textuals) [Abstract] |  |  |
Ownership percentage in equity method investment | 50.00% |  |
Whitby [Member] |  |  |
Basis Of Presentation and Summary of Significant Accounting Policies (Textuals) [Abstract] |  |  |
Ownership percentage in equity method investment | 50.00% |  |
Calpine Receivables [Member] |  |  |
Basis Of Presentation and Summary of Significant Accounting Policies (Textuals) [Abstract] |  |  |
Ownership percentage in equity method investment | 100.00% |  |
West [Member] |  |  |
Basis Of Presentation and Summary of Significant Accounting Policies (Textuals) [Abstract] |  |  |
Impairment losses | $ 0 | 28 | 13
Texas [Member] |  |  |
Basis Of Presentation and Summary of Significant Accounting Policies (Textuals) [Abstract] |  |  |
Impairment losses | 0 | 13 | 0
East [Member] |  |  |
Basis Of Presentation and Summary of Significant Accounting Policies (Textuals) [Abstract] |  |  |
Impairment losses | 10 | 0 | $ 0
North American Power [Member] |  |  |
Jointly Owned Plants [Abstract] |  |  |
Goodwill, Acquired During Period |  | $ 49 |
Russell City Energy [Member] |  |  |
Basis Of Presentation and Summary of Significant Accounting Policies (Textuals) [Abstract] |  |  |
Long-term Debt | 341 |  |
Property, Plant and Equipment, Net | 676 |  |
Los Esteros Project [Member] |  |  |
Basis Of Presentation and Summary of Significant Accounting Policies (Textuals) [Abstract] |  |  |
Long-term Debt | 163 |  |
Property, Plant and Equipment, Net | 439 |  |
Minimum [Member] |  |  |
Basis Of Presentation and Summary of Significant Accounting Policies (Textuals) [Abstract] |  |  |
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification | 180 |  |
Maximum [Member] |  |  |
Basis Of Presentation and Summary of Significant Accounting Policies (Textuals) [Abstract] |  |  |
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification | $ 200 |  |

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