Revenue From Contracts With Customers - Schedule Of Disaggregated Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Disaggregation of Revenue [Line Items]
Net revenues	$ 212,575	$ 163,260	$ 581,462	$ 418,117
Minimum contract duration to be classified as long-term			12 months
Well Intervention
Disaggregation of Revenue [Line Items]
Net revenues	154,441		$ 445,769
Robotics
Disaggregation of Revenue [Line Items]
Net revenues	54,340		120,569
Production Facilities
Disaggregation of Revenue [Line Items]
Net revenues	15,877		48,541
Intercompany Elimination
Disaggregation of Revenue [Line Items]
Net revenues	(12,083)		(33,417)
Short-term
Disaggregation of Revenue [Line Items]
Net revenues	69,425		217,560
Short-term | Well Intervention
Disaggregation of Revenue [Line Items]
Net revenues	39,548		143,510
Short-term | Robotics
Disaggregation of Revenue [Line Items]
Net revenues	29,877		74,050
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	143,150		363,902
Long-term | Well Intervention
Disaggregation of Revenue [Line Items]
Net revenues	114,893		302,259
Long-term | Robotics
Disaggregation of Revenue [Line Items]
Net revenues	24,463		46,519
Long-term | Production Facilities
Disaggregation of Revenue [Line Items]
Net revenues	15,877		48,541
Long-term | Intercompany Elimination
Disaggregation of Revenue [Line Items]
Net revenues	$ (12,083)		$ (33,417)