Business Segment Information - Total Assets By Reportable Segment (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Segment Reporting Information [Line Items]
Total assets	$ 2,596,731	$ 2,347,730
Reportable Segments | Well Intervention
Segment Reporting Information [Line Items]
Total assets	2,180,180	1,916,638
Reportable Segments | Robotics
Segment Reporting Information [Line Items]
Total assets	151,478	147,602
Reportable Segments | Production Facilities
Segment Reporting Information [Line Items]
Total assets	142,624	120,845
Corporate and Other
Segment Reporting Information [Line Items]
Total assets	$ 122,449	$ 162,645