Revenue From Contracts With Customers - Disaggregation Of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Disaggregation of Revenue [Line Items]
Net revenues	$ 212,609	$ 212,575	$ 581,160	$ 581,462
Intercompany Eliminations
Disaggregation of Revenue [Line Items]
Net revenues	(23,283)	(12,083)	(51,398)	(33,417)
Well Intervention
Disaggregation of Revenue [Line Items]
Net revenues	170,206	154,441	451,511	445,769
Well Intervention | Intercompany Eliminations
Disaggregation of Revenue [Line Items]
Net revenues	(15,318)	(4,379)	(28,355)	(10,546)
Robotics
Disaggregation of Revenue [Line Items]
Net revenues	51,909	54,340	136,396	120,569
Robotics | Intercompany Eliminations
Disaggregation of Revenue [Line Items]
Net revenues	(7,965)	(7,704)	(23,043)	(22,871)
Production Facilities
Disaggregation of Revenue [Line Items]
Net revenues	13,777	15,877	44,651	48,541
Short-term
Disaggregation of Revenue [Line Items]
Net revenues	79,827	69,425	226,051	217,560
Short-term | Intercompany Eliminations
Disaggregation of Revenue [Line Items]
Net revenues	0	0	0	0
Short-term | Well Intervention
Disaggregation of Revenue [Line Items]
Net revenues	53,018	39,548	145,611	143,510
Short-term | Robotics
Disaggregation of Revenue [Line Items]
Net revenues	26,809	29,877	80,440	74,050
Short-term | Production Facilities
Disaggregation of Revenue [Line Items]
Net revenues	0	0	0	0
Long-term
Disaggregation of Revenue [Line Items]
Net revenues	132,782	143,150	355,109	363,902
Long-term | Intercompany Eliminations
Disaggregation of Revenue [Line Items]
Net revenues	(23,283)	(12,083)	(51,398)	(33,417)
Long-term | Well Intervention
Disaggregation of Revenue [Line Items]
Net revenues	117,188	114,893	305,900	302,259
Long-term | Robotics
Disaggregation of Revenue [Line Items]
Net revenues	25,100	24,463	55,956	46,519
Long-term | Production Facilities
Disaggregation of Revenue [Line Items]
Net revenues	$ 13,777	$ 15,877	$ 44,651	$ 48,541