Operations by Business Segment and Geographic Area Operations by Business Segment and Geographic Area - Other Significant Reconciling Items (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Segment Reporting, Asset Reconciling Item [Line Items]
Property, Plant and Equipment, Additions	$ 142,513	$ 423,988	$ 426,671
Oil And Gas [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Property, Plant and Equipment, Additions	136,520	413,141	420,644
ROVs [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Property, Plant and Equipment, Additions	50,339	57,558	188,848
Subsea Products [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Property, Plant and Equipment, Additions	56,669	69,434	112,851
Subsea Projects [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Property, Plant and Equipment, Additions	25,602	276,308	91,918
Asset Integrity [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Property, Plant and Equipment, Additions	3,910	9,841	27,027
Advanced Technologies [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Property, Plant and Equipment, Additions	2,742	5,015	2,352
Corporate and Other [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Property, Plant and Equipment, Additions	$ 3,251	$ 5,832	$ 3,675