Discontinued Operations (Components of income (loss) from discontinued operations, net of tax) (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Income Statement Additional Disclosures by Disposal Groups Including Discontinued Operations [Line Items]
Income tax expense (benefit)	$ 0	$ (275)	$ 0	$ (1,991)
Income (Loss) from Discontinued Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	(4,085)	(4,610)	(8,577)	(24,107)
Segment, Discontinued Operations [Member]
Income Statement Additional Disclosures by Disposal Groups Including Discontinued Operations [Line Items]
Revenues		588		18,694
Income (Loss) from Discontinued Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	$ (4,085)	(4,610)	$ (8,577)	(24,107)
Segment Conventional Decommissioning Business [Member]
Income Statement Additional Disclosures by Disposal Groups Including Discontinued Operations [Line Items]
Income (Loss) from Discontinued Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest		$ 500		$ 1,600

Amount of tax expense (benefit) related to a discontinued operation. Includes, but is not limited to, tax expense (benefit) related to income (loss) from operations during the phase-out period, tax expense (benefit) related to gain (loss) on disposal, tax expense (benefit) related to gain (loss) for reversal of write-down (write-down) to fair value, less cost to sell, and tax expense (benefit) related to adjustments of a prior period gain (loss) on disposal.

Amount after tax of income (loss) from a discontinued operation including the portion attributable to the noncontrolling interest. Includes, but is not limited to, the income (loss) from operations during the phase-out period, gain (loss) on disposal, gain (loss) for reversal of write-down (write-down) to fair value, less cost to sell, and adjustments to a prior period gain (loss) on disposal.

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