Organization (Details)	12 Months Ended
	Dec. 31, 2017 segment	Feb. 23, 2018 vessel
Segment Reporting Information [Line Items]
Number of reportable segments | segment	3
Scenario, Forecast [Member] | Well Intervention [Member]
Segment Reporting Information [Line Items]
Number of chartered vessels		2
Scenario, Forecast [Member] | Robotics [Member]
Segment Reporting Information [Line Items]
Number of chartered vessels		3