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Risk Management Activities and Derivative Transactions Counterparty Credit Risk (Details) $ in Millions | Mar. 31, 2018 USD ($) merchants megawatts
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Derivative |  |
Number of active future commission merchants | merchants | 2 |
Total derivatives not subject to master netting or similar arrangement | $ | $ 15 | [1]
Megawatts of Power Purchase Agreement |  |
Derivative |  |
Megawatts | megawatts | 440 |
[1] | There are no derivative contracts subject to a master netting arrangement or similar agreement that are not offset in the consolidated balance sheets.

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- Definition Fair value of financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset, not subject to a master netting arrangement. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 55 -Paragraph 22 -URI http://asc.fasb.org/extlink&oid=82849420&loc=SL20226052-175313 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 50 -Paragraph 3 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312 + Details
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- Details
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