Discontinued Operations (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Impairment Included in Discontinued Operations			$ 119,300
Long-term assets	$ 92,634	$ 91,940
Subsea Construction Marine Vessels Member
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Impairment Included in Discontinued Operations	25,800		98,300
Gain on sale of assets, disposal group accounted for as discontinued operations		$ 18,800
Subsea Construction Intangible Assets Member
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Impairment Included in Discontinued Operations			15,400
Conventional Decommissioning Long-lived Assets Member
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Impairment Included in Discontinued Operations	$ 8,800		$ 5,600