Business Segment Information - Financial Data By Business Segment (Details) - USD ($) $ in Thousands	3 Months Ended			6 Months Ended
	Jun. 30, 2015	Mar. 31, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Segment Reporting Information [Line Items]
Revenue	$ 810,303	$ 786,772	$ 927,407	$ 1,597,075	$ 1,767,608
Income from Operations	107,940	106,650	161,311	214,590	294,173
Oil And Gas [Member]
Segment Reporting Information [Line Items]
Revenue	724,316	712,241	861,954	1,436,557	1,640,132
Income from Operations	138,763	139,497	197,100	278,260	362,978
ROVs [Member]
Segment Reporting Information [Line Items]
Revenue	216,426	219,447	268,274	435,873	524,093
Income from Operations	61,294	62,182	75,825	123,476	152,565
Subsea Products [Member]
Segment Reporting Information [Line Items]
Revenue	240,057	240,729	327,252	480,786	587,262
Income from Operations	42,286	50,014	79,497	92,300	134,013
Subsea Projects [Member]
Segment Reporting Information [Line Items]
Revenue	172,324	153,572	136,199	325,896	274,389
Income from Operations	30,607	22,276	25,863	52,883	46,400
Asset Integrity [Member]
Segment Reporting Information [Line Items]
Revenue	95,509	98,493	130,229	194,002	254,388
Income from Operations	4,576	5,025	15,915	9,601	30,000
Advanced Technologies [Member]
Segment Reporting Information [Line Items]
Revenue	85,987	74,531	65,453	160,518	127,476
Income from Operations	6,267	5,020	198	11,287	3,153
Unallocated Expenses [Member]
Segment Reporting Information [Line Items]
Income from Operations	$ (37,090)	$ (37,867)	$ (35,987)	$ (74,957)	$ (71,958)