Business Segment Information (Narrative) (Details)	6 Months Ended
	Jun. 30, 2014 segment
Segment Reporting Information [Line Items]
Number of reportable segments	4
Monohull Vessels [Member]
Segment Reporting Information [Line Items]
Number of vessels under construction	2
Well Intervention [Member]
Segment Reporting Information [Line Items]
Number of vessels under construction	2
Robotics [Member] | Short Term [Member]
Segment Reporting Information [Line Items]
Number of chartered vessels	2
Robotics [Member] | Long Term [Member]
Segment Reporting Information [Line Items]
Number of chartered vessels	5