Business Segment Information - Total Assets By Reportable Segment (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Segment Reporting Information [Line Items]
Total assets	$ 2,366,490	$ 2,246,941
Corporate and Other [Member]
Segment Reporting Information [Line Items]
Total assets	270,153	305,331
Well Intervention [Member] | Reportable Segments [Member]
Segment Reporting Information [Line Items]
Total assets	1,774,821	1,596,517
Robotics [Member] | Reportable Segments [Member]
Segment Reporting Information [Line Items]
Total assets	179,777	186,901
Production Facilities [Member] | Reportable Segments [Member]
Segment Reporting Information [Line Items]
Total assets	$ 141,739	$ 158,192