Company Overview	6 Months Ended
Jun. 30, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Company Overview	Company Overview We are an international offshore energy services company that provides specialty services to the offshore energy industry, with a focus on well intervention and robotics operations. We seek to provide services and methodologies that we believe are critical to maximizing production economics. We provide services primarily in deepwater in the U.S. Gulf of Mexico, North Sea, Asia Pacific and West Africa regions, and have recently expanded our operations into Brazil with the commencement of operations of the Siem Helix 1. Our “life of field” services are segregated into three reportable business segments: Well Intervention, Robotics and Production Facilities (Note 11). Our Well Intervention segment includes our vessels and equipment used to perform well intervention services primarily in the U.S. Gulf of Mexico, North Sea and Brazil. Our Well Intervention segment also includes intervention riser systems (“IRSs”), some of which we rent out on a stand-alone basis, and subsea intervention lubricators (“SILs”). Our well intervention vessels include the Q4000, the Q5000, the Seawell, the Well Enhancer and the two chartered vessels, the Siem Helix 1 which is used and the Siem Helix 2 which is to be used, in connection with our contracts to provide well intervention services offshore Brazil. We also have a semi-submersible well intervention vessel under construction, the Q7000. Our Robotics segment includes remotely operated vehicles (“ROVs”), trenchers and ROVDrills designed to complement offshore construction and well intervention services, and currently operates four chartered ROV support vessels, including the Grand Canyon III that went into service for us in May 2017. Our Production Facilities segment includes the Helix Producer I (the “HP I”), a ship-shaped dynamic positioning floating production vessel, and the Helix Fast Response System (the “HFRS”), which provides certain operators access to our Q4000 and HP I vessels in the event of a well control incident in the Gulf of Mexico. The HP I has been under contract to process production from the Phoenix field for the field operator since February 2013. We currently operate under a fixed fee agreement for the HP I for service to the Phoenix field until at least June 1, 2023. We are party to an agreement providing various operators with access to the HFRS for well control purposes, which was amended effective February 1, 2017 to reduce the retainer fee and to extend the term of the agreement by one year to March 31, 2019. The Production Facilities segment also includes our ownership interest in Independence Hub, LLC (“Independence Hub”) and previously included our former ownership interest in Deepwater Gateway, L.L.C. (“Deepwater Gateway”) that we sold in February 2016 (Note 5).

Company Overview

We are an international offshore energy services company that provides specialty services to the offshore energy industry, with a focus on well intervention and robotics operations. We seek to provide services and methodologies that we believe are critical to maximizing production economics. We provide services primarily in deepwater in the U.S. Gulf of Mexico, North Sea, Asia Pacific and West Africa regions, and have recently expanded our operations into Brazil with the commencement of operations of the Siem Helix 1. Our “life of field” services are segregated into three reportable business segments: Well Intervention, Robotics and Production Facilities (Note 11).

Our Well Intervention segment includes our vessels and equipment used to perform well intervention services primarily in the U.S. Gulf of Mexico, North Sea and Brazil. Our Well Intervention segment also includes intervention riser systems (“IRSs”), some of which we rent out on a stand-alone basis, and subsea intervention lubricators (“SILs”). Our well intervention vessels include the Q4000, the Q5000, the Seawell, the Well Enhancer and the two chartered vessels, the Siem Helix 1 which is used and the Siem Helix 2 which is to be used, in connection with our contracts to provide well intervention services offshore Brazil. We also have a semi-submersible well intervention vessel under construction, the Q7000.

Our Robotics segment includes remotely operated vehicles (“ROVs”), trenchers and ROVDrills designed to complement offshore construction and well intervention services, and currently operates four chartered ROV support vessels, including the Grand Canyon III that went into service for us in May 2017.

Our Production Facilities segment includes the Helix Producer I (the “HP I”), a ship-shaped dynamic positioning floating production vessel, and the Helix Fast Response System (the “HFRS”), which provides certain operators access to our Q4000 and HP I vessels in the event of a well control incident in the Gulf of Mexico. The HP I has been under contract to process production from the Phoenix field for the field operator since February 2013. We currently operate under a fixed fee agreement for the HP I for service to the Phoenix field until at least June 1, 2023. We are party to an agreement providing various operators with access to the HFRS for well control purposes, which was amended effective February 1, 2017 to reduce the retainer fee and to extend the term of the agreement by one year to March 31, 2019. The Production Facilities segment also includes our ownership interest in Independence Hub, LLC (“Independence Hub”) and previously included our former ownership interest in Deepwater Gateway, L.L.C. (“Deepwater Gateway”) that we sold in February 2016 (Note 5).