Amount before amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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Amount of loss from the write-down of an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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Losses recognized in the current period on contracts which are expected to generate losses, which are probable and can be reasonably estimated, in a future period.

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Goodwill Goodwill Narrative (Details) (USD $)	12 Months Ended			1 Months Ended
Goodwill Goodwill Narrative (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	May 31, 2013	May 01, 2012
Goodwill [Line Items]
Goodwill impairment	$ (977,000)us-gaap_GoodwillImpairmentLoss	$ (173,249,000)us-gaap_GoodwillImpairmentLoss	$ 0us-gaap_GoodwillImpairmentLoss
Finite-Lived Intangible Assets, Gross	748,148,000	804,281,000
Electricity Operating Segment [Member]
Goodwill [Line Items]
Goodwill impairment	(977,000)	(173,249,000)
Incremental Goodwill Impairment Expense Determined After Close of 2013 Accounting Records [Member]
Goodwill [Line Items]
Goodwill impairment	(977,000)
Expected Loss Recognized Resulting from Inclusion of Certain Integration Costs not Originally Reflected in Acquisition Valuation Model [Member]
Goodwill [Line Items]
Loss on Contracts				2,400,000
Customer Relationship Associated with Error Adjustment - Balance Prior to Correction of Error [Member]
Goodwill [Line Items]
Finite-Lived Intangible Assets, Gross					$ 1,500,000