Commitments and Contingencies - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	9 Months Ended	0 Months Ended
	Sep. 30, 2014	Dec. 16, 2005 Antoine, et al. vs. J. Ray McDermott, Inc., et al. [Member] LegalMatter	Jan. 29, 2007 Antoine, et al. vs. J. Ray McDermott, Inc., et al. [Member] Judicial District Court for Harris County, Texas [Member] LegalMatter	Apr. 04, 2014 Antoine, et al. vs. J. Ray McDermott, Inc., et al. [Member] Judicial District Court for Harris County, Texas [Member] Maritime products [Member] LegalMatter	Jan. 29, 2007 Antoine, et al. vs. J. Ray McDermott, Inc., et al. [Member] Judicial District Court for Harris County, Texas [Member] Maritime products [Member] LegalMatter	Jan. 29, 2007 Boudreaux, et al. v. McDermott, Inc., et al. [Member] United States District Court for the Southern District of Texas [Member] 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	20		21
Number of defendants		215	65		42	30
Environmental reserves included in current liabilities	$ 4.0
Aggregate possible liquidated damage due to failure to meet specified contractual milestone dates, offshore oil and gas construction segment	128.2
Liquidated damage contingencies, accrued	39.3
Trigger dates, potential liquidated damages	2015-06
Outstanding obligation in 2014	104.1
Outstanding obligation in 2015	233.0
Outstanding obligation	$ 337.1