Property And Equipment (Tables)

12 Months Ended

Dec. 31, 2017

Property, Plant and Equipment [Abstract]

Summary of gross components of property and equipment

The following is a summary of the gross components of property and equipment (dollars in thousands):

		December 31,
	Estimated Useful Life	2017		2016
Vessels	15 to 30 years	$	2,083,267	$	1,860,379
ROVs, trenchers and ROVDrills	10 years	298,227		309,603
Machinery, equipment and leasehold improvements	5 to 15 years	314,278		280,908
Total property and equipment		$	2,695,772	$	2,450,890