Business Segment Information - Intercompany Segment Revenues (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Segment Reporting Information [Line Items]
Net revenues	$ (180,716)	$ (193,490)	$ (506,072)	$ (573,658)
Well Intervention
Segment Reporting Information [Line Items]
Net revenues	(131,314)	(140,803)	(397,387)	(427,296)
Robotics
Segment Reporting Information [Line Items]
Net revenues	(42,623)	(49,802)	(96,430)	(135,896)
Intercompany Eliminations
Segment Reporting Information [Line Items]
Net revenues	11,773	11,282	36,962	32,835
Intercompany Eliminations | Well Intervention
Segment Reporting Information [Line Items]
Net revenues	4,267	4,120	17,060	11,334
Intercompany Eliminations | Robotics
Segment Reporting Information [Line Items]
Net revenues	$ 7,506	$ 7,162	$ 19,902	$ 21,501