Business Segment Information - Total Assets By Reportable Segment (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Segment Reporting Information [Line Items]
Total assets	$ 2,613,511	$ 2,347,730
Corporate and Other
Segment Reporting Information [Line Items]
Total assets	137,956	162,645
Well Intervention | Reportable Segments
Segment Reporting Information [Line Items]
Total assets	2,133,205	1,916,638
Robotics | Reportable Segments
Segment Reporting Information [Line Items]
Total assets	183,125	147,602
Production Facilities | Reportable Segments
Segment Reporting Information [Line Items]
Total assets	$ 159,225	$ 120,845