Revenue (Details) - USD ($) $ in Thousands	3 Months Ended			6 Months Ended
	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Segment Reporting Information [Line Items]
Revenues	$ 478,674	$ 416,413	$ 515,036	$ 895,087	$ 961,212
Rovs Member
Segment Reporting Information [Line Items]
Revenues	107,426	85,594	103,432	193,020	197,454
Subsea Products Member
Segment Reporting Information [Line Items]
Revenues	121,704	126,688	174,893	248,392	325,532
Subsea Projects Member
Segment Reporting Information [Line Items]
Revenues	78,036	56,860	75,545	134,896	138,501
Asset Integrity [Member]
Segment Reporting Information [Line Items]
Revenues	67,422	61,288	58,192	128,710	110,850
Oil And Gas [Member]
Segment Reporting Information [Line Items]
Revenues	374,588	330,430	412,062	705,018	772,337
Advanced Technologies Member
Segment Reporting Information [Line Items]
Revenues	$ 104,086	$ 85,983	$ 102,974	$ 190,069	$ 188,875