Business Segment Information - Total Assets By Reportable Segment (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Segment Reporting Information [Line Items]
Total assets	$ 2,607,321	$ 2,347,730
Corporate and Other
Segment Reporting Information [Line Items]
Total assets	130,016	162,645
Well Intervention | Reportable Segments
Segment Reporting Information [Line Items]
Total assets	2,104,002	1,916,638
Robotics | Reportable Segments
Segment Reporting Information [Line Items]
Total assets	190,473	147,602
Production Facilities | Reportable Segments
Segment Reporting Information [Line Items]
Total assets	$ 182,830	$ 120,845