Business Segment Information - Summary Of Intercompany Segment Revenues (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Net revenues	$ (163,266)	$ (163,260)	$ (150,329)	$ (104,528)	$ (128,031)	$ (161,245)	$ (107,267)	$ (91,039)	$ (581,383)	$ (487,582)	$ (695,802)
Intercompany Elimination [Member]
Segment Reporting Information [Line Items]
Net revenues									42,065	39,356	54,473
Intercompany Elimination [Member] | Well Intervention [Member]
Segment Reporting Information [Line Items]
Net revenues									11,489	8,442	22,855
Intercompany Elimination [Member] | Robotics [Member]
Segment Reporting Information [Line Items]
Net revenues									$ 30,576	$ 30,914	$ 31,618