Summary Of Significant Accounting Policies (Property, Plant And Equipment) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Property, Plant and Equipment [Line Items]
Property and equipment	$ 2,241,444	$ 1,963,706
Vessels [Member]
Property, Plant and Equipment [Line Items]
Property and equipment	1,657,448	1,403,573
ROVs Trenchers And ROVDrills [Member]
Property, Plant and Equipment [Line Items]
Property and equipment	310,841	271,801
Property, plant and equipment, useful life	10 years
Machinery, Equipment, Buildings And Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property and equipment	$ 273,155	$ 288,332
Maximum [Member] | Vessels [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	30 years
Maximum [Member] | Machinery, Equipment, Buildings And Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	30 years
Minimum [Member] | Vessels [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	15 years
Minimum [Member] | Machinery, Equipment, Buildings And Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	5 years