Summary Of Major Accounting Policies Summary of Major Accounting Policies - Inventory (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Inventory [Line Items]
Inventory Write-down	$ 0	$ 30,490	$ 25,990
Subsea Products Member
Inventory [Line Items]
Inventory Write-down		5,300	10,285
ROVs [Member]
Inventory [Line Items]
Inventory Write-down		$ 25,200	$ 15,700