v3.19.1

Income Taxes (Deferred Tax Assets and Liabilities) (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016
Valuation Allowance [Line Items] |  |  |
Income Tax Expense (Benefit), Intraperiod Tax Allocation | $ 1 | $ 6 | $ 0
NOL and credit carryforwards | 1,595 | 1,810 |
Taxes related to risk management activities and derivatives | 7 | 20 |
Reorganization items and impairments | 166 | 146 |
Deferred Tax Assets, Other | 101 | 28 |
Deferred tax assets before valuation allowance | 1,869 | 2,004 |
Valuation allowance | (1,000) | (1,168) |
Valuation Allowance, Deferred Tax Asset, Change in Amount | 168 | 413 | $ 56
Total deferred tax assets | 869 | 836 |
Deferred tax liabilities: property, plant and equipment | (890) | (805) |
Deferred Tax Liabilities, Gross | (890) | (805) |
Deferred Tax Liabilities, Net | (21) |  |
Net deferred tax asset (liability) |  | 31 |
Deferred Tax Liabilities, Gross, Noncurrent | (22) | (28) |
Deferred income tax asset, non-current | 1 | $ 59 |
Change in Valuation due to Merger [Member] |  |  |
Valuation Allowance [Line Items] |  |  |
Valuation Allowance, Deferred Tax Asset, Change in Amount | $ (58) |  |

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