Fair Value Measurements (Significant unobservalbe inputs, nonrecurring) (Details) (East Bend Station [Member])	12 Months Ended
Dec. 31, 2014
East Bend Station [Member]
Fair Value Measurements, Valuation Techniques	Discounted cash flows

Description of the inputs and valuation technique(s) used to measure fair value.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (bbb)

-URI http://asc.fasb.org/extlink&oid=36462937&loc=d3e19207-110258

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