Revenue From Contracts With Customers - Schedule Of Disaggregated Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Disaggregation of Revenue [Line Items]
Net revenues	$ 204,625	$ 150,329	$ 368,887	$ 254,857
Minimum contract duration to be classified as long-term			12 months
Well Intervention
Disaggregation of Revenue [Line Items]
Net revenues	161,759		$ 291,328
Robotics
Disaggregation of Revenue [Line Items]
Net revenues	39,060		66,229
Production Facilities
Disaggregation of Revenue [Line Items]
Net revenues	16,343		32,664
Intercompany Elimination
Disaggregation of Revenue [Line Items]
Net revenues	(12,537)		(21,334)
Short-term
Disaggregation of Revenue [Line Items]
Net revenues	92,673		155,024
Short-term | Well Intervention
Disaggregation of Revenue [Line Items]
Net revenues	61,935		103,962
Short-term | Robotics
Disaggregation of Revenue [Line Items]
Net revenues	30,738		51,062
Short-term | Production Facilities
Disaggregation of Revenue [Line Items]
Net revenues	0		0
Short-term | Intercompany Elimination
Disaggregation of Revenue [Line Items]
Net revenues	0		0
Long-term
Disaggregation of Revenue [Line Items]
Net revenues	111,952		213,863
Long-term | Well Intervention
Disaggregation of Revenue [Line Items]
Net revenues	99,824		187,366
Long-term | Robotics
Disaggregation of Revenue [Line Items]
Net revenues	8,322		15,167
Long-term | Production Facilities
Disaggregation of Revenue [Line Items]
Net revenues	16,343		32,664
Long-term | Intercompany Elimination
Disaggregation of Revenue [Line Items]
Net revenues	$ (12,537)		$ (21,334)