Revenue From Contracts With Customers - Disaggregation Of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Disaggregation of Revenue [Line Items]
Net revenues	$ 166,823	$ 164,262
Intercompany Eliminations
Disaggregation of Revenue [Line Items]
Net revenues	(9,702)	(8,797)
Well Intervention
Disaggregation of Revenue [Line Items]
Net revenues	122,231	129,569
Well Intervention | Intercompany Eliminations
Disaggregation of Revenue [Line Items]
Net revenues	(3,225)	(1,952)
Robotics
Disaggregation of Revenue [Line Items]
Net revenues	39,041	27,169
Robotics | Intercompany Eliminations
Disaggregation of Revenue [Line Items]
Net revenues	(6,477)	(6,845)
Production Facilities
Disaggregation of Revenue [Line Items]
Net revenues	15,253	16,321
Short-term
Disaggregation of Revenue [Line Items]
Net revenues	54,735	62,351
Short-term | Intercompany Eliminations
Disaggregation of Revenue [Line Items]
Net revenues	0	0
Short-term | Well Intervention
Disaggregation of Revenue [Line Items]
Net revenues	29,805	42,027
Short-term | Robotics
Disaggregation of Revenue [Line Items]
Net revenues	24,930	20,324
Short-term | Production Facilities
Disaggregation of Revenue [Line Items]
Net revenues	0	0
Long-term
Disaggregation of Revenue [Line Items]
Net revenues	112,088	101,911
Long-term | Intercompany Eliminations
Disaggregation of Revenue [Line Items]
Net revenues	(9,702)	(8,797)
Long-term | Well Intervention
Disaggregation of Revenue [Line Items]
Net revenues	92,426	87,542
Long-term | Robotics
Disaggregation of Revenue [Line Items]
Net revenues	14,111	6,845
Long-term | Production Facilities
Disaggregation of Revenue [Line Items]
Net revenues	$ 15,253	$ 16,321