Business Segment Information - Total Assets By Reportable Segment (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Segment Reporting Information [Line Items]
Total assets	$ 2,620,222	$ 2,347,730
Corporate and Other
Segment Reporting Information [Line Items]
Total assets	143,839	162,645
Well Intervention | Reportable Segments
Segment Reporting Information [Line Items]
Total assets	2,111,752	1,916,638
Robotics | Reportable Segments
Segment Reporting Information [Line Items]
Total assets	187,401	147,602
Production Facilities | Reportable Segments
Segment Reporting Information [Line Items]
Total assets	$ 177,230	$ 120,845