Business Segment Information - Financial Data By Business Segment (Details) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended
	Sep. 30, 2015	Jun. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Segment Reporting Information [Line Items]
Revenue	$ 743,613	$ 810,303	$ 973,089	$ 2,340,688	$ 2,740,697
Income from Operations	113,464	107,940	181,918	328,054	476,091
Oil And Gas [Member]
Segment Reporting Information [Line Items]
Revenue	661,265	724,316	908,424	2,097,822	2,548,556
Income from Operations	135,886	138,763	218,702	414,146	581,680
ROVs [Member]
Segment Reporting Information [Line Items]
Revenue	198,426	216,426	285,385	634,299	809,478
Income from Operations	52,417	61,294	88,350	175,893	240,915
Subsea Products [Member]
Segment Reporting Information [Line Items]
Revenue	220,039	240,057	336,745	700,825	924,007
Income from Operations	46,079	42,286	83,430	138,379	217,443
Subsea Projects [Member]
Segment Reporting Information [Line Items]
Revenue	147,191	172,324	151,560	473,087	425,949
Income from Operations	28,841	30,607	27,339	81,724	73,739
Asset Integrity [Member]
Segment Reporting Information [Line Items]
Revenue	95,609	95,509	134,734	289,611	389,122
Income from Operations	8,549	4,576	19,583	18,150	49,583
Advanced Technologies [Member]
Segment Reporting Information [Line Items]
Revenue	82,348	85,987	64,665	242,866	192,141
Income from Operations	1,635	6,267	2,863	12,922	6,016
Unallocated Expenses [Member]
Segment Reporting Information [Line Items]
Income from Operations	$ (24,057)	$ (37,090)	$ (39,647)	$ (99,014)	$ (111,605)