Business Segment Information - Intercompany Segment Revenues (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Segment Reporting Information [Line Items]
Net revenues	$ (193,490)	$ (212,609)	$ (573,658)	$ (581,160)
Well Intervention
Segment Reporting Information [Line Items]
Net revenues	(140,803)	(170,206)	(427,296)	(451,511)
Robotics
Segment Reporting Information [Line Items]
Net revenues	(49,802)	(51,909)	(135,896)	(136,396)
Intercompany Eliminations
Segment Reporting Information [Line Items]
Net revenues	11,282	23,283	32,835	51,398
Intercompany Eliminations | Well Intervention
Segment Reporting Information [Line Items]
Net revenues	4,120	15,318	11,334	28,355
Intercompany Eliminations | Well Intervention | Production Facilities
Segment Reporting Information [Line Items]
Net revenues		10,600		15,900
Intercompany Eliminations | Robotics
Segment Reporting Information [Line Items]
Net revenues	$ 7,162	$ 7,965	$ 21,501	$ 23,043