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Price Risk Management Future year net unrealized gain/loss recorded at balance sheet date expected to become realized (Details) (Gain (Loss) on Derivatives [Member], USD $) In Millions, unless otherwise specified | 12 Months Ended | 48 Months Ended
--- | --- | ---
Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2013 | Dec. 31, 2012 | Dec. 31, 2015
Gain (Loss) on Derivatives [Member] |  |  |  |  |
Commodity contracts: [Abstract] |  |  |  |  |
Commodity Contracts, Electricity | $ 8 | $ 21 | $ 42 | $ 64 | $ 135
Commodity Contracts, Natural Gas | 6 | 24 | 72 | 132 | 234
Net unrealized loss | $ 14 | $ 45 | $ 114 | $ 196 | $ 369

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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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