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Commitments and Contingencies, Asset Retirement Obligations (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2018 | Dec. 31, 2017
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward] |  |
Beginning balance | $ 2,475 | $ 2,782
Liabilities Incurred | 13 | 1
Liabilities Settled | (14) | (30)
Accretion | 120 | 136
Cash flow revisions | (26) | (414)
Ending balance | 2,568 | 2,475
Legally restricted assets, for purposes of funding future nuclear decommissioning | 2,055 |
Electric Plant Nuclear Production Decommissioning |  |
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward] |  |
Beginning balance | 1,874 | 2,249
Liabilities Incurred | 0 | 0
Liabilities Settled | 0 | 0
Accretion | 94 | 114
Cash flow revisions | 0 | (489)
Ending balance | 1,968 | 1,874
Electric Plant Wind Production |  |
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward] |  |
Beginning balance | 96 | 92
Liabilities Incurred | 12 | 0
Liabilities Settled | 0 | 0
Accretion | 4 | 4
Cash flow revisions | 7 | 0
Ending balance | 119 | 96
Electric Plant Steam, Hydro and Other Production Asbestos |  |
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward] |  |
Beginning balance | 192 | 205
Liabilities Incurred | 0 | 1
Liabilities Settled | (14) | (29)
Accretion | 8 | 9
Cash flow revisions | (9) | 6
Ending balance | 177 | 192
Electric Plant Electric Distribution |  |
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward] |  |
Beginning balance | 21 | 20
Liabilities Incurred | 0 | 0
Liabilities Settled | 0 | 0
Accretion | 1 | 1
Cash flow revisions | 20 | 0
Ending balance | 42 | 21
Electric Plant Other |  |
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward] |  |
Beginning balance | 5 | 5
Liabilities Incurred | 0 | 0
Liabilities Settled | 0 | 0
Accretion | 0 | 0
Cash flow revisions | 2 | 0
Ending balance | 7 | 5
Natural Gas Plant Gas Transmission and Distribution |  |
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward] |  |
Beginning balance | 282 | 205
Liabilities Incurred | 0 | 0
Liabilities Settled | 0 | 0
Accretion | 13 | 8
Cash flow revisions | (46) | 69
Ending balance | 249 | 282
Natural Gas Plant Other |  |
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward] |  |
Beginning balance | 4 | 4
Liabilities Incurred | 0 | 0
Liabilities Settled | 0 | 0
Accretion | 0 | 0
Cash flow revisions | 0 | 0
Ending balance | 4 | 4
Common and Other Property Common Miscellaneous |  |
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward] |  |
Beginning balance | 1 | 2
Liabilities Incurred | 0 | 0
Liabilities Settled | 0 | (1)
Accretion | 0 | 0
Cash flow revisions | 0 | 0
Ending balance | 1 | 1
Non utility and other |  |
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward] |  |
Beginning balance | 0 |
Liabilities Incurred | 1 |
Liabilities Settled | 0 |
Accretion | 0 |
Cash flow revisions | 0 |
Ending balance | $ 1 | $ 0

X
- Definition The carrying amount of a liability for an asset retirement obligation. An asset retirement obligation is a legal obligation associated with the disposal or retirement of a tangible long-lived asset that results from the acquisition, construction or development, or the normal operations of a long-lived asset, except for certain obligations of lessees. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 410 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=6392692&loc=d3e7535-110849 + Details
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- Definition Amount of accretion expense recognized during the period that is associated with an asset retirement obligation. Accretion expense measures and incorporates changes due to the passage of time into the carrying amount of the liability. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 410 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (c)(3) -URI http://asc.fasb.org/extlink&oid=6392692&loc=d3e7535-110849 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 410 -SubTopic 20 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6392676&loc=d3e7480-110848 + Details
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- Definition Amount of asset retirement obligations settled, or otherwise disposed of, during the period. This may include asset retirement obligations transferred to third parties associated with the sale of a long-lived asset. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 410 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=6392692&loc=d3e7535-110849 + Details
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- Definition Amount of increase (decrease) in the asset retirement obligation from changes in the amount or timing of the estimated cash flows associated with the settlement of the obligation. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 410 -SubTopic 20 -Section 35 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=6392603&loc=d3e7123-110846 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 410 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (c)(4) -URI http://asc.fasb.org/extlink&oid=6392692&loc=d3e7535-110849 + Details
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- Definition The fair value of investments held in a trust fund to pay for the costs of decontaminating and decommissioning facilities, whether such amount is presented as a separate caption or as a parenthetical disclosure on the balance sheet. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 410 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6392692&loc=d3e7535-110849 + Details
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