Business Segment Information - Summary Of Financial Data By Segment (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended								12 Months Ended
	Dec. 31, 2016	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
Income (loss) from operations										51,543	(1,130)	(63,235)
Net interest expense										13,751	18,778	31,239
Other non-operating income (expense), net										(6,794)	(464)	559
Income (loss) before income taxes										30,998	(20,372)	(93,915)
Capital expenditures										137,083	231,127	186,487
Depreciation and amortization										110,522	108,745	114,187
Gain on disposition of assets, net										146	(39)	1,290
Goodwill impairment										0	0	45,107
Helix 534
Segment Reporting Information [Line Items]
Gain on disposition of assets, net	$ 1,300
Reportable Segments
Segment Reporting Information [Line Items]
Income (loss) from operations										100,852	38,616	(23,479)
Intercompany Eliminations
Segment Reporting Information [Line Items]
Net revenues										(44,139)	(42,065)	(39,356)
Corporate, Eliminations and Other
Segment Reporting Information [Line Items]
Income (loss) from operations										(49,309)	(39,746)	(39,756)
Capital expenditures										443	125	(199)
Depreciation and amortization										334	2,882	5,995
Well Intervention
Segment Reporting Information [Line Items]
Net revenues										560,568
Well Intervention | Helix 534
Segment Reporting Information [Line Items]
Gain on disposition of assets, net	$ 1,300
Well Intervention | Reportable Segments
Segment Reporting Information [Line Items]
Net revenues										560,568	406,341	294,000
Income (loss) from operations										87,643	52,733	14,910
Capital expenditures										136,164	230,354	185,892
Depreciation and amortization										76,943	68,301	68,392
Well Intervention | Intercompany Eliminations
Segment Reporting Information [Line Items]
Net revenues										(14,218)	(11,489)	(8,442)
Robotics
Segment Reporting Information [Line Items]
Net revenues										158,989
Goodwill impairment												45,100
Robotics | Reportable Segments
Segment Reporting Information [Line Items]
Net revenues										158,989	152,755	160,580
Income (loss) from operations										(14,054)	(42,289)	(72,250)
Capital expenditures										151	648	720
Depreciation and amortization										19,175	23,626	25,848
Robotics | Intercompany Eliminations
Segment Reporting Information [Line Items]
Net revenues										(29,921)	(30,576)	(30,914)
Production Facilities
Segment Reporting Information [Line Items]
Net revenues										64,400
Production Facilities | Reportable Segments
Segment Reporting Information [Line Items]
Net revenues										64,400	64,352	72,358
Income (loss) from operations										27,263	28,172	33,861
Capital expenditures										325	0	74
Depreciation and amortization										$ 14,070	$ 13,936	$ 13,952