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Price Risk Management Future Year Net Unrealized Gain/Loss Recorded at Balance Sheet Date Expected to Become Realized (Details) (Unrealized Gain Loss On Derivatives [Member], USD $) In Millions, unless otherwise specified | 3 Months Ended | 12 Months Ended | 51 Months Ended
--- | --- | --- | ---
Dec. 31, 2013 | Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2017
Unrealized Gain Loss On Derivatives [Member] |  |  |  |  |  |
Commodity contracts: |  |  |  |  |  |
Electricity | $ 8 | $ 0 | $ 7 | $ 23 | $ 40 | $ 78
Natural gas | 21 | 4 | 11 | 11 | 34 | 81
Net unrealized loss | $ 29 | $ 4 | $ 18 | $ 34 | $ 74 | $ 159

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- Details
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- Definition Net unrealized gain or loss related to commodity contracts recorded as of the balance sheet date, expected to be realized in the statement of income in a future period as a result of the settlement of the underlying derivative instrument. + References No definition available. + Details
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- Definition Net unrealized gain or loss recorded as of the balance sheet date related to commodity contracts for electricity, expected to be realized in the statement of income in a future period as a result of the settlement of the underlying derivative instrument. + References No definition available. + Details
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- Definition Net unrealized gain or loss recorded as of the balance sheet date related to commodity contracts for natural gas, expected to be realized in the statement of income in a future period as a result of the settlement of the underlying derivative instrument. + References No definition available. + Details
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