Business Segment Information (Summary Of Financial Data By Segment) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended					9 Months Ended
	Sep. 30, 2013		Jun. 30, 2013	Sep. 30, 2012		Sep. 30, 2013		Sep. 30, 2012
Segment Reporting Information [Line Items]
Revenues	$ 220,117			$ 217,110		$ 649,724		$ 644,413
Income (loss) from operations	62,659			20,216		125,094		77,153
Equity in earnings of investments	857			1,392		2,150		7,547
Gain (loss) on sale of assets	15,812		(1,100)	(12,933)		14,727		(12,933)
Well Intervention [Member]
Segment Reporting Information [Line Items]
Revenues	114,238			88,711		319,893		274,249
Income (loss) from operations	33,544			17,405		93,906		53,647
Robotics [Member]
Segment Reporting Information [Line Items]
Revenues	90,370			95,107		242,940		238,762
Income (loss) from operations	16,392			22,627		28,991		50,301
Subsea Construction [Member]
Segment Reporting Information [Line Items]
Revenues	4,120			37,673		69,305		162,581
Income (loss) from operations	15,088	[1]		(7,020)	[1]	29,031	[1]	7,411	[1]
Gain (loss) on sale of assets	15,600		(1,100)
Production Facilities [Member]
Segment Reporting Information [Line Items]
Revenues	24,366			20,024		68,933		60,009
Income (loss) from operations	14,136			10,180		39,964		30,111
Corporate and Other [Member]
Segment Reporting Information [Line Items]
Income (loss) from operations	(16,522)			(23,015)		(64,260)		(61,434)
Intercompany Elimination [Member]
Segment Reporting Information [Line Items]
Revenues	(12,977)			(24,405)		(51,347)		(91,188)
Income (loss) from operations	$ 21			$ 39		$ (2,538)		$ (2,883)

[1] The 2013 amounts include the $1.1 million loss on the sale of the Caesar in June 2013 and the $15.6 million gain on the sale of the Express in July 2013 (Note 2).