Business Segment Information - Intercompany Segment Revenues (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Segment Reporting Information [Line Items]
Net revenues	$ (199,147)	$ (201,728)	$ (380,168)	$ (368,551)
Well Intervention
Segment Reporting Information [Line Items]
Net revenues	(145,841)	(159,074)	(286,493)	(281,305)
Robotics
Segment Reporting Information [Line Items]
Net revenues	(50,836)	(45,446)	(86,094)	(84,487)
Intercompany Eliminations
Segment Reporting Information [Line Items]
Net revenues	11,123	18,413	21,553	28,115
Intercompany Eliminations | Well Intervention
Segment Reporting Information [Line Items]
Net revenues	3,910	9,812	7,214	13,037
Intercompany Eliminations | Well Intervention | Production Facilities
Segment Reporting Information [Line Items]
Net revenues		5,300		5,300
Intercompany Eliminations | Robotics
Segment Reporting Information [Line Items]
Net revenues	$ 7,213	$ 8,601	$ 14,339	$ 15,078