Computation of Basic and Diluted Earnings Per Share (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended														12 Months Ended
	Dec. 31, 2013		Sep. 30, 2013		Jun. 30, 2013		Mar. 31, 2013	Dec. 31, 2012		Sep. 30, 2012		Jun. 30, 2012		Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Earnings Per Share [Abstract]
Income from continuing operations less noncontrolling interest	$ (323,973)	[1]	$ (64,070)	[2]	$ (149,423)	[3]	$ 20,553	$ 40,544	[4]	$ 50,612	[5]	$ 52,739	[6]	$ 59,261	$ (516,913)	$ 203,156	$ 151,542
Income (loss) from discontinued operations, net of tax														3,497		3,497	(12,812)
Net Income (Loss) Attributable to McDermott International, Inc.	$ (323,973)	[1]	$ (64,070)	[2]	$ (149,423)	[3]	$ 20,553	$ 40,544	[4]	$ 50,612	[5]	$ 52,739	[6]	$ 62,758	$ (516,913)	$ 206,653	$ 138,730
Weighted average common shares (basic)															236,514,584	235,638,422	234,598,901
Effect of dilutive securities:
Stock options, restricted stock and performance shares																1,981,266	2,441,606
Adjusted weighted average common shares (diluted)															236,514,584	237,619,688	237,040,507
Basic earnings per common share:
Income from continuing operations less noncontrolling interest	$ (1.37)	[1]	$ (0.27)	[2]	$ (0.63)	[3]	$ 0.09	$ 0.17	[4]	$ 0.21	[5]	$ 0.22	[6]	$ 0.25	$ (2.19)	$ 0.86	$ 0.65
Income (loss) from discontinued operations, net of tax														$ 0.01		$ 0.01	$ (0.05)
Net income attributable to McDermott International, Inc.	$ (1.37)	[1]	$ (0.27)	[2]	$ (0.63)	[3]	$ 0.09	$ 0.17	[4]	$ 0.21	[5]	$ 0.22	[6]	$ 0.27	$ (2.19)	$ 0.88	$ 0.59
Diluted earnings per common share:
Income from continuing operations less noncontrolling interest	$ (1.37)	[1]	$ (0.27)	[2]	$ (0.63)	[3]	$ 0.09	$ 0.17	[4]	$ 0.21	[5]	$ 0.22	[6]	$ 0.25	$ (2.19)	$ 0.86	$ 0.64
Income (loss) from discontinued operations, net of tax														$ 0.01		$ 0.01	$ (0.05)
Net income attributable to McDermott International, Inc.	$ (1.37)	[1]	$ (0.27)	[2]	$ (0.63)	[3]	$ 0.09	$ 0.17	[4]	$ 0.21	[5]	$ 0.22	[6]	$ 0.26	$ (2.19)	$ 0.87	$ 0.59

[1] Operating income for the quarter ended December 31, 2013 was influenced by increased cost estimates, impairment losses and restructuring charges.

[2] Operating income for the quarter ended September 30, 2013 was influenced by increased project losses.

[3] Operating income for the quarter ended June 30, 2013 was influenced by increased cost estimates on projects in our Middle East and Asia Pacific segments, as well as restructuring charges.

[4] Operating income for the quarter ended December 31, 2012 was influenced by significant cost savings on marine installation activities on an EPCI project, partially offset by project losses of approximately $52.0 million.

[5] Revenues for the quarter ended September 30, 2012 were influenced by increased marine activity on certain of our Asia Pacific projects.

[6] Operating income for the quarter ended June 30 2012 was influenced by increased fabrication activities, partially offset by lower project close-outs and settlements.