Business Segment Information - Financial Data By Reportable Segment (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Segment Reporting Information [Line Items]
Net revenues	$ 212,609	$ 212,575	$ 581,160	$ 581,462
Income (loss) from operations	38,998	31,377	62,339	55,033
Reportable Segments
Segment Reporting Information [Line Items]
Income (loss) from operations	49,615	46,722	93,830	90,875
Intercompany Eliminations
Segment Reporting Information [Line Items]
Net revenues	(23,283)	(12,083)	(51,398)	(33,417)
Corporate, Eliminations and Other
Segment Reporting Information [Line Items]
Income (loss) from operations	(10,617)	(15,345)	(31,491)	(35,842)
Well Intervention
Segment Reporting Information [Line Items]
Net revenues	170,206	154,441	451,511	445,769
Well Intervention | Reportable Segments
Segment Reporting Information [Line Items]
Net revenues	170,206	154,441	451,511	445,769
Income (loss) from operations	37,689	34,427	74,002	82,774
Well Intervention | Intercompany Eliminations
Segment Reporting Information [Line Items]
Net revenues	(15,318)	(4,379)	(28,355)	(10,546)
Robotics
Segment Reporting Information [Line Items]
Net revenues	51,909	54,340	136,396	120,569
Robotics | Reportable Segments
Segment Reporting Information [Line Items]
Net revenues	51,909	54,340	136,396	120,569
Income (loss) from operations	8,876	5,601	7,921	(12,818)
Robotics | Intercompany Eliminations
Segment Reporting Information [Line Items]
Net revenues	(7,965)	(7,704)	(23,043)	(22,871)
Production Facilities
Segment Reporting Information [Line Items]
Net revenues	13,777	15,877	44,651	48,541
Production Facilities | Reportable Segments
Segment Reporting Information [Line Items]
Net revenues	13,777	15,877	44,651	48,541
Income (loss) from operations	$ 3,050	$ 6,694	$ 11,907	$ 20,919