Revenue From Contracts With Customers - Disaggregation Of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Disaggregation of Revenue [Line Items]
Net revenues	$ 201,728	$ 204,625	$ 368,551	$ 368,887
Intercompany Eliminations
Disaggregation of Revenue [Line Items]
Net revenues	(18,413)	(12,537)	(28,115)	(21,334)
Well Intervention
Disaggregation of Revenue [Line Items]
Net revenues	159,074	161,759	281,305	291,328
Well Intervention | Intercompany Eliminations
Disaggregation of Revenue [Line Items]
Net revenues	(9,812)	(4,215)	(13,037)	(6,167)
Robotics
Disaggregation of Revenue [Line Items]
Net revenues	45,446	39,060	84,487	66,229
Robotics | Intercompany Eliminations
Disaggregation of Revenue [Line Items]
Net revenues	(8,601)	(8,322)	(15,078)	(15,167)
Production Facilities
Disaggregation of Revenue [Line Items]
Net revenues	15,621	16,343	30,874	32,664
Short-term
Disaggregation of Revenue [Line Items]
Net revenues	91,489	92,673	146,224	155,024
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	62,788	61,935	92,593	103,962
Short-term | Robotics
Disaggregation of Revenue [Line Items]
Net revenues	28,701	30,738	53,631	51,062
Short-term | Production Facilities
Disaggregation of Revenue [Line Items]
Net revenues	0	0	0	0
Long-term
Disaggregation of Revenue [Line Items]
Net revenues	110,239	111,952	222,327	213,863
Long-term | Intercompany Eliminations
Disaggregation of Revenue [Line Items]
Net revenues	(18,413)	(12,537)	(28,115)	(21,334)
Long-term | Well Intervention
Disaggregation of Revenue [Line Items]
Net revenues	96,286	99,824	188,712	187,366
Long-term | Robotics
Disaggregation of Revenue [Line Items]
Net revenues	16,745	8,322	30,856	15,167
Long-term | Production Facilities
Disaggregation of Revenue [Line Items]
Net revenues	$ 15,621	$ 16,343	$ 30,874	$ 32,664