Business Segment Information - Summary Of Intercompany Segment Revenues (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting Information [Line Items]
Net revenues	$ 158,356	$ 212,575	$ 204,625	$ 164,262	$ 163,266	$ 163,260	$ 150,329	$ 104,528	$ 739,818	$ 581,383	$ 487,582
Well Intervention
Segment Reporting Information [Line Items]
Net revenues									560,568
Robotics
Segment Reporting Information [Line Items]
Net revenues									158,989
Intercompany Eliminations
Segment Reporting Information [Line Items]
Net revenues									(44,139)	(42,065)	(39,356)
Intercompany Eliminations | Well Intervention
Segment Reporting Information [Line Items]
Net revenues									(14,218)	(11,489)	(8,442)
Intercompany Eliminations | Robotics
Segment Reporting Information [Line Items]
Net revenues									$ (29,921)	$ (30,576)	$ (30,914)