Business Segment Information - Financial Data By Reportable Segment (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Segment Reporting Information [Line Items]
Net revenues	$ 201,728	$ 204,625	$ 368,551	$ 368,887
Income (loss) from operations	23,072	24,772	23,341	23,656
Reportable Segments
Segment Reporting Information [Line Items]
Income (loss) from operations	34,073	37,234	44,215	44,153
Intercompany Eliminations
Segment Reporting Information [Line Items]
Net revenues	(18,413)	(12,537)	(28,115)	(21,334)
Corporate, Eliminations and Other
Segment Reporting Information [Line Items]
Income (loss) from operations	(11,001)	(12,462)	(20,874)	(20,497)
Well Intervention
Segment Reporting Information [Line Items]
Net revenues	159,074	161,759	281,305	291,328
Well Intervention | Reportable Segments
Segment Reporting Information [Line Items]
Net revenues	159,074	161,759	281,305	291,328
Income (loss) from operations	26,672	34,470	36,313	48,347
Well Intervention | Intercompany Eliminations
Segment Reporting Information [Line Items]
Net revenues	(9,812)	(4,215)	(13,037)	(6,167)
Robotics
Segment Reporting Information [Line Items]
Net revenues	45,446	39,060	84,487	66,229
Robotics | Reportable Segments
Segment Reporting Information [Line Items]
Net revenues	45,446	39,060	84,487	66,229
Income (loss) from operations	2,949	(4,102)	(955)	(18,419)
Robotics | Intercompany Eliminations
Segment Reporting Information [Line Items]
Net revenues	(8,601)	(8,322)	(15,078)	(15,167)
Production Facilities
Segment Reporting Information [Line Items]
Net revenues	15,621	16,343	30,874	32,664
Production Facilities | Reportable Segments
Segment Reporting Information [Line Items]
Net revenues	15,621	16,343	30,874	32,664
Income (loss) from operations	$ 4,452	$ 6,866	$ 8,857	$ 14,225