Business Segment Information - Financial Data By Business Segment (Details) - USD ($) $ in Thousands	3 Months Ended			12 Months Ended
	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018	Dec. 31, 2018
Segment Reporting Information [Line Items]
Revenue	$ 493,886	$ 495,095	$ 416,413	$ 495,095
Income (Loss) from Operations	(21,714)	(97,144)	(27,149)
Depreciation and amortization	52,486	128,916	54,128
Oil and Gas [Member]
Segment Reporting Information [Line Items]
Revenue	379,607	378,370	330,430
Income (Loss) from Operations	3,121	(83,108)	(1,323)
Depreciation and amortization	50,497	127,005	51,828
Remotely Operated Vehicles [Member]
Segment Reporting Information [Line Items]
Revenue	100,346	96,736	85,594
Income (Loss) from Operations	1,418	(1,275)	(2,398)
Depreciation and amortization	27,990	27,972	27,642
Subsea Products [Member]
Segment Reporting Information [Line Items]
Revenue	128,844	129,509	126,688
Income (Loss) from Operations	(476)	(3,803)	1,755
Depreciation and amortization	12,991	11,797	14,025
Subsea Projects [Member]
Segment Reporting Information [Line Items]
Revenue	89,728	89,295	56,860
Income (Loss) from Operations	2,892	(79,379)	(2,359)
Depreciation and amortization	7,882	85,651	8,313
Asset Integrity [Member]
Segment Reporting Information [Line Items]
Revenue	60,689	62,830	61,288
Income (Loss) from Operations	(713)	1,349	1,679
Depreciation and amortization	1,634	1,585	1,848
Advanced Technologies [Member]
Segment Reporting Information [Line Items]
Revenue	114,279	116,725	85,983
Income (Loss) from Operations	9,599	15,406	1,668
Depreciation and amortization	830	786	766
Unallocated Expenses [Member]
Segment Reporting Information [Line Items]
Income (Loss) from Operations	(34,434)	(29,442)	(27,494)
Depreciation and amortization	$ 1,159	$ 1,125	$ 1,534