Commitments and Contingencies - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	9 Months Ended	1 Months Ended				9 Months Ended
	Sep. 30, 2013	Dec. 16, 2005 Antoine, et al. vs. J. Ray McDermott, Inc., et al. LegalMatter	Jan. 29, 2007 Antoine, et al. vs. J. Ray McDermott, Inc., et al. Judicial District Court for Harris County, Texas LegalMatter	Jan. 29, 2007 Antoine, et al. vs. J. Ray McDermott, Inc., et al. Judicial District Court for Harris County, Texas Maritime products LegalMatter	Jan. 29, 2007 Boudreaux, et al. v. McDermott, Inc., et al. United States District Court for the Southern District of Texas LegalMatter	Sep. 30, 2013 Class Action Complaints against MII, Stephen M. Johnson and Perry L. Elders United States District Court for the Southern District of Texas LegalMatter
Commitments and Contingencies Disclosure [Line Items]
Legal claims	On December 16, 2005, a proceeding entitled Antoine, et al. vs. J. Ray McDermott, Inc., et al.(“Antoine Suit”), was filed in the 24th Judicial District Court, Jefferson Parish, Louisiana, by approximately 88 plaintiffs against approximately 215 defendants, including our subsidiaries formerly known as JRMI and Delta Hudson Engineering Corporation (“DHEC”), generally alleging injuries for exposure to asbestos, and unspecified chemicals, metals and noise while the plaintiffs were allegedly employed as Jones Act seamen. This case was dismissed by the Court on January 10, 2007, without prejudice to plaintiffs’ rights to refile their claims. On January 29, 2007, 21 plaintiffs from the dismissed Antoine Suit filed a matter entitled Boudreaux, et al. v. McDermott, Inc., et al. (the “Boudreaux Suit”), in the United States District Court for the Southern District of Texas, against JRMI and our subsidiary formerly known as McDermott Incorporated, and approximately 30 other employer defendants, alleging Jones Act seaman status and generally alleging exposure to welding fumes, solvents, dyes, industrial paints and noise. The Boudreaux Suit was transferred to the United States District Court for the Eastern District of Louisiana on May 2, 2007, which entered an order in September 2007 staying the matter until further order of the Court due to the bankruptcy filing of one of the co-defendants.
Number of plaintiffs		88	43		21	2
Number of defendants		215	65	42	30
Environmental reserves, current	$ 0
Aggregate possible liquidated damage due to failure to meet specified contractual milestone dates, offshore oil and gas construction segment	137.0
Liquidated damage contingencies, accrued	11.0
Trigger dates, potential liquidated damages	2013-11
Outstanding obligation in 2013	41.6
Outstanding obligation in 2014	136.5
Outstanding obligation 2015	204.3
Outstanding obligation	$ 382.4