COMMITMENTS AND CONTINGENCIES - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended	9 Months Ended
	Jun. 30, 2011	Sep. 30, 2011 LegalMatter	Apr. 09, 2009 Entity	Dec. 31, 2005 LegalMatter	Sep. 30, 2011 Minimum Oceanografia S.A. de C.V. v. McDermott Gulf Operating Company, Inc. and Secunda Marine Services, Inc.	Apr. 13, 2010 Minimum Oceanografia S.A. de C.V. v. McDermott Gulf Operating Company, Inc. and Secunda Marine Services, Inc.	Jan. 03, 2005 Counterclaim LegalMatter	Jan. 29, 2007 Boudreaux, et al. v. McDermott, Inc., et al. United States District Court for the Southern District of Texas LegalMatter	Jan. 29, 2007 Boudreaux, et al. v. McDermott, Inc., et al. United States District Court for the Southern District of Texas Other Employers than JRMI and MI LegalMatter	Jan. 10, 2007 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 Other Employers than JRMI and MI LegalMatter	Jan. 29, 2007 Antoine, et al. vs. J. Ray McDermott, Inc., et al. Judicial District Court for Harris County, Texas Maritime products LegalMatter	Sep. 30, 2011 Minimum	Sep. 30, 2011 Maximum
Commitments and Contingencies Disclosure [Line Items]
Number of subsidiaries involved in lawsuit			2
Damages for loss of revenue and physical damage to the equipment, punitive damages, attorneys' fees and costs claimed by Oceanografia Sociedad Asnonima					$ 25	$ 10
Plaintiffs' claims pending				13			20
Number of claimants agreed for settlement		13
Legal claims		In a proceeding entitled Antoine, et al. vs. J. Ray McDermott, Inc., et al., filed in the 24th Judicial District Court, Jefferson Parish, Louisiana, approximately 88 plaintiffs filed suit against approximately 215 defendants, including JRMI and Delta Hudson Engineering Corporation (“DHEC”), another affiliate of ours, generally alleging injuries for exposure to asbestos, and unspecified chemicals, metals and noise while the plaintiffs were allegedly employed as Jones Act seamen. On January 10, 2007, the District Court dismissed the plaintiffs’ claims, without prejudice to their right to refile their claims. On January 29, 2007, in a matter entitled Boudreaux, et al. v. McDermott, Inc., et al., originally filed in the United States District Court for the Southern District of Texas, 21 plaintiffs originally named in the Antoine matter filed suit against JRMI, MI and approximately 30 other employer defendants, alleging Jones Act seaman status and generally alleging exposure to welding fumes, solvents, dyes, industrial paints and noise. Boudreaux was transferred to the United States District Court for the Eastern District of Louisiana on May 2, 2007. The District Court 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. Additionally, on January 29, 2007, in a matter entitled Antoine, et al. v. McDermott, Inc., et al., filed in the 164th Judicial District Court for Harris County, Texas, 43 plaintiffs originally named in the Antoine matter filed suit against JRMI, MI and approximately 65 other employer defendants and 42 maritime products defendants, alleging Jones Act seaman status and generally alleging personal injuries for exposure to asbestos and noise. On April 27, 2007, the District Court entered an order staying all activity and deadlines in this matter other than service of process and answer/appearance dates until further order of the Court. The Antoine plaintiffs filed a motion to lift the stay on February 20, 2009, which is pending before the Texas District Court. The plaintiffs seek monetary damages in an unspecified amount in both cases and attorneys’ fees in the new Antoine case.
Number of plaintiffs								21		88	43
Number of defendants									30	215		65	42
Environmental reserve		1.7
Environmental reserve, current		0.9
Aggregate possible liquidated damage due to failure to meet specified contractual milestone dates, Offshore Oil and Gas Construction segment		55
Liquidated damage contingencies, accrued		10
Surety bonds issued		76.2
Environmental reserve recovered	$ 2.0
Trigger dates, potential liquidated damages														2011-02	2012-06