Annual report pursuant to Section 13 and 15(d)

Operating Segments - Narrative (Details)

v3.8.0.1
Operating Segments - Narrative (Details)
12 Months Ended
Dec. 31, 2017
segment
Dec. 31, 2016
segment
Dec. 31, 2015
jacket
segment
Segment Reporting [Abstract]      
Number of operating divisions 3 3 3
Number of corporate non-operating divisions 1    
Number of newly-formed operating divisions 1    
Number of jackets and piles constructed | jacket     5