Discontinued Operations (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017
Subsea Construction Marine Vessels [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Loss from discontinued operations	$ 0.7	$ 18.9

Amount before tax of gain (loss) not previously recognized resulting from the disposal of a discontinued operation.

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