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Discontinued Operations and Dispositions - Summarized of Results of Discontinued Operations (Details) - USD ($) $ in Millions | 3 Months Ended
--- | ---
Mar. 31, 2019 | Mar. 31, 2018
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] |  |
Gain/(Loss) from discontinued operations, net of tax | $ 388 | $ (5)
Discontinued Operations | South Central Portfolio |  |
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] |  |
Operating revenues | 31 | 102
Operating costs and expenses | (23) | (86)
Loss from discontinued operations, net of tax | 8 | 16
Gain on disposal of discontinued operations, net of tax | 27 | 0
Gain/(Loss) from discontinued operations, net of tax | 35 | 16
Discontinued Operations | Carlsbad Energy Holdings LLC |  |
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] |  |
Operating revenues | 19 | 260
Operating costs and expenses | (9) | (230)
Other expenses | (5) | (58)
Gain/(loss) from operations of discontinued components, before tax | 5 | (28)
Income tax expense | 0 | (7)
Loss from discontinued operations, net of tax | 5 | (21)
Gain on disposal of discontinued operations, net of tax | 348 | 0
Gain/(Loss) from discontinued operations, net of tax | $ 353 | $ (21)

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